Have you not heard about the rail strikes that will last until Xmas?
You'll be lucky to find a train never mind one with bike space.
It's both impossible and unnecessary to make a reservation for a bike with some operators eg Northern, and with others, such as TransPennine, although you must make a reservation, making one is no guarantee at all that you can actually take your bike on the train. Best work out your route first then check the operator's websites individually wrt bike policy and proceed accordingly - phone calls or an in-person visit to a railway booking office might be needed to clarify matters.
Anyone know how to reserve a place on a train for your bike? I had a look on the TrainLine app, but couldn't find anything on there to make a bike reservation for your journey. Thanks
From bitter experience, it can be a minefield if you are travelling any distance involving multiple trains with different operators.
Locally, it couldn't be easier. Just turn up and put your bike on the train and go! That is Scotrail on the Clyde coast routes, but you don't have to go far for the policy to be different. e.g. still with Scotrail - do not even attempt to travel on the Glasgow/Inverness line without a bike reservation, and they only take 4 per train. Strictly enforced, too.
It's not always easy
You should try booking a bike onto the Eurostar....
Unless it's one of the train operators like Anglia who have different policies on different services, which national rail unhelpfully list all the policies for all services, leaving people confused, scared and/or none the wiser.First thing to do is go to nationalrail.co.uk journey planner and find the service you want. Then click the little bike icon This will enable you to find the operator, their bike policy, and whether reservations are required.