Staying in London and interested in going to Windsor Castle and Bath by train in one day. Doable?
It's possible. The train from Paddington to Bath Spa goes thru Slough. Get off there and catch the frequent train to Windsor. A tour of the castle will probably take at least an hour. (The station at Bath is known as "Bath Spa.") Take the train back to Slough and continue on to Bath Spa on another train. I think you would need separate tickets. One from Paddington station to Windsor via Slough, and one to Bath Spa from Slough. Returning, you will need a ticket for Bath Spa to Paddington. You won't have a lot of time in either place, but you could spend a couple of hours in each.
Thank you!