It might sound obvious but only bring as much luggage as you can manage.
You can take up to 3 pieces of luggage free of charge on trains within the UK. This includes 2 large items (suitcase, rucksack etc.) and one smaller item of hand luggage (handbag, briefcase etc.) Luggage should be stored in the overhead luggage racks, under the seats and in the luggage compartments throughout the train. They must not obstruct the gangways for safety reasons and should not be placed on seats, these are for paying passengers.
On some longer distance trains, it might be possible to store luggage in a separate area of the train. Speak to the staff on the platform or on the train before boarding and they will be able to help you with this. This does mean that you will be separated from your luggage, so make sure it’s locked.
Prams/ pushchairs can be carried on trains, but the must be capable of folding if required.
Sporting equipment can only be taken on board at the discretion of the train operator you are traveling with so please check their website before travelling
For information on taking a bike on board, please see Do I need to reserve a space for my bike?