You are unlikely to find snow in England at Christmas - possibly ice on untreated roads, but there is a small army of gritting lorries which deal with freezing conditions - if you stick to main roads as much as possible, they get the treatment first.

Central London does 'do' New Year, but it is a bit of a scrum and hoiking drunks out of the fountains in Trafalgar Square is what London bobbies are usually doing to bring in the New Year. However - there are usually parties going on in every city centre, but local knowledge helps so you know the best part of town to be in on the night. Sometimes only a few hundred yards divides civilised night life from the dangers of drunken barbarian hordes.

Pubs often have a shut off time, and if you are not in there by then, you don't get in. Some sell tickets as well.

If money is likely to be a bit tight you could try booking the trains in advance over the internet. You might need to get your relatives to order and pay for the tickets and post them on to you, or some other faffing about, but it can reduce costs considerably. You can also get return tickets which cost less than the fare one way and other oddities, but you might have to book on a specific train for that, and travel on it - the tickets are not transferable, but if you can get your travel timetable sorted out then you can save yourself some money.