Get a room you two!
Oh…
Travelling from London, long distance needs bikes to be booked on, and on return journeys. This can’t be done online annoyingly, so ‘phoning to book tickets is best unless you are passing the station before you travel. Rules will state you can’t lock bikes up, certainly not to any fixed part of the train, but I always use a cable lock to prevent someone running off with me bike/slow them down a bit at least. Even better if two or more of you are travelling, lock bikes to each other. Pretty safe though tbh. Great Western trains have more space than Virgin. Try to book seats as close to bikes as poss.
Shorter journeys, just turn up and bung bike on board. If the bike storage area is full of luggage put there by ignorant dickheads, just get the guard to tell everyone to either move their bags and cases, or the train doesn’t move. 🙂
Oh, and be prepared for people giving you dirty looks. Just give them one back.
Try not to stab them in the neck with a Biro.