I am interested in leaving London via the train, stopping to see Windsor Castle and then going on via public transportation to Bath where I will start my Rick Steves tour. My issue is I will have my suitcase with me and I need a place to store it while I go see the castle. Any suggestions?
At the entrance to Windsor Castle, you and your belongings will be subject to airport-style security checks.
There is a security cloakroom in the China Museum at the entrance to the State Apartments for the storage of large items of baggage. Large backpacks are not permitted in the State Apartments and must be checked in here. You can reclaim your bags from this cloakroom at the end of your visit to Windsor Castle.
Read about it here on their website:
I hope that you'll be packing light, both for the purposes of the tour and because you'll have a few changes of train on this travel day (0 or 1 toward Windsor and then 2 toward Bath).