Rail Travel

Tickets
The good news is that up to 2 children under the age of 5 may travel with each fare-paying adult for free. Be aware however, on busy services, you could well be asked to seat your under 5 year old on your lap if another full-fare passenger needs a seat. A discounted child ticket can resolve this, especially important on busy (but long) train journeys.
For older children, up to the age of 15 inclusive, there is just a 50% ticket charge on most trains.
It is always a good idea to purchase train tickets well in advance with great advance prices available on http://www.nationalrail.co.uk/ By buying in advance then you can have reserved seats together (on trains where that service exists). Although it is worth double checking the seat numbers you are allocated, as we have been issued facing seats as opposed to adjacent seats.
If a fair amount of train travel is expected (for example over the holidays), and your children are over 5 years old, then I would highly recommend The Family and Friends Railcard. http://www.familyandfriends-railcard.co.uk/what-do-you-get/features  While you do have to pay up front for this railcard, it will then save you 1/3 off adult tickets and 60% off children’s tickets.
It is also worth noting the group saver system for rail travel in England and Wales, which is free.
GroupSave offers the opportunity for three or four people (minimum one adult) to travel for the price that two adults would normally pay on various off-peak ticket types. Up to four additional children can accompany the main party, and travel at the flat fare of £1 each, single or return (not valid on ScotRail). In addition two children under the age of five can travel free of charge with each fare-paying passenger. GroupSave is NOT available for travel on Stansted Express services. Children may travel in the place of Adults on an Adult ticket to take advantage of this offer. There must be at least one adult in each group.
 
While most stations in the UK have made improvements to their accessibility and facilities, there are still differences. If any particular aspect of station facility is important to you, then check the station in advance at http://www.nationalrail.co.uk/stations_destinations/
 
Food and Drink
On-board, there will generally be a buffet card or trolley service, but this is not guaranteed. Also worth remembering is the limited menu, meaning that you are probably better off supplying your own food on rail journeys, at least for just the children. This is pretty much the same as you would expect on a short flight. As with Airports, train stations can often supply you with a number of food and drink options. The favourite suppliers being WHSmith, Whistlestop and at smaller stations; an independent newsagents or tea shop. A limited refreshment service might also be available on the station platforms.
Points to remember are the weight or size of the food you take with you as you will have to carry it through the station and then the carriage. Also, if there is not a lift or escalator, as is common at smaller stations, then you will likely have to negotiate stairs to get to another platform. Also, try and choose food that is easy to handle and limited in its mess-making capabilities. This is due to the stopping and starting of the train at stations and the leaning of trains as they negotiate bends.
 
Entertainment
With many carriages having a big table between four facing seats, entertainment space doesn’t have to be an issue. Just remember that, like the food and drink you take with you, you will have to be aware of weight.
Kids can have great little rucksacks now, so for older toddlers and children you can suggest they choose the toys they want to fill the bag to entertain them. Colouring, sets of pencils/crayons, a picture book and small Aquadoodle are all popular options in our house. For younger toddlers similar things work, but you will become the chooser and carrier of the entertainment.
A DVD player can be a good form of entertainment for toddlers and older children. The only issue is the life of the battery and that there is no way of charging it on the train. A better alternative is a tablet, or even your smart phone. Movies, cartoons or apps are great entertainment from about 2 years up. Add child-friendly ear phones and you have a self-contained child.
For babies, often just the new sights and sounds can be interesting, but it is good to take along a few loved toys. Board books or fabric books are also useful. 
 
Safety
As they say on the London Underground ‘mind the gap’. Many modern trains are a lot easier to access than older carriages. Wider doors, no slam doors and more level platform/carriage floors mean that access is better but little legs will still struggle though -  stepping on to the train and up stairs & escalators.
Be aware too of the crowds that are often found at stations, especially at city centres & airports and during rush hours. People are on such a mission, that a young child can be easily caught up in it.
 
Queues / Waiting
There will always be crowds of people at large stations and during rush hours. The most likely places for queues will be at the ticket desk, going through the ticket barriers and boarding. Stay tight together and holding hands and go for it.
With the ticket barriers remember that you can use the end gate, the one that opens wider and usually has a conductor by it. This is so much easier to negotiate when you have a buggy, bags, and / or a walking child.
Timing getting on the train can be a difficult equation. You don’t want to be too early or children and babies might become bored or cabin fever might set in too early. But, if you do not have reserved seats, then you don’t want to be the last on the train.
 
Additional pointers
It is worth warning about train changes. If there is a change of train on your journey, make sure you are comfortable with the time given for the change. We had a situation earlier this year when we were very grateful we were not travelling with our children. Despite moving as fast as possible through the London Underground from Victoria to King’s Cross, we only just made our train. With hindsight we would get the earlier train to Victoria or use a taxi instead of the underground. This is especially true if we had our girls with us.
 
Toilets – at small and medium sized stations toilets are mostly free. At large stations, such as London Victoria, you can expect a minimum of a 30p charge. This is also the case if you need the baby change room.
On trains the toilets can vary greatly too. On older rolling stock, the toilet is very small, right by the train doors and traditional in every sense. On newer trains, one end of a carriage could well incorporate a large space for wheelchair use, a few flip-up seats and a very large disabled toilet. These are excellent areas for a family with a buggy to sit (obviously as long as a wheelchair doesn’t need it).