Day trip to Bath from London

Amber, if you happen to be a hard core Jane Austen fan, you might be interested in trying out Sally Lunn's Bunns as a place/thing to eat. Yes heavily touristed, but sometimes curiosity wins, and they're good. Google it for info. The rest of the city's connection to J.A. is tenuous at best.

Its hard to fit much into a day trip, but they do have a free walking tour twice a day that leaves in front of the Roman Baths, that is worth it for a quick overview. Check the timing and coordinate to meet it.

I’ve done it as a day trip on a November weekday 2 years ago (Christmas market was on) and was by myself, so I could move at my own pace. Also, I’d seen the baths and the pump room on a prior visit, so I skipped those last visit. With all that said, here goes:

Took morning train from Paddington.
Visited Bath Abbey interior.
Walked through inside market.
Had tea at Jane Austen Centre (did not tour the center just ate there).
Went to Museum of Costume/Fashion.
Walked over to Royal Crescent to take photos.
Walked back down hill and strolled some of the side streets.
Stopped at Marks & Spencer (en route to train) for a drink and snack before boarding evening train.
Visited Christmas market stalls along the way.
Note: there is a large Waitrose near the public library if you want to stop in a grocery to pick up anything.

I think if you have never visited the Roman baths, that should be a priority stop during your trip.
Bath is lovely. Have a great time!

I really liked the Museum of East Asian Art and the Holburne Museum. I found the architecture too repetitive to hold my interest for long.

Bath is one of my favorite cities!

Here would be my priorities for a first timer:

• Roman Baths
• Walking tour is there is one at a convenient time. The first time I went I did one of the paid ones instead of the bigger free ones from the Mayor's office. I toured with Sue from this company. http://www.bathtours.org.uk/ I've also done one from the Jane Austen Centre but that was during the JA Festival so not sure if they offer them all the time.
• If you don't want to do a walking tour, stop by the TI and pick up a map of Bath, then after you see the Baths, walk up to the Royal Crescent to see the Regency era buildings then imagine the ladies in Georgian times being carried down the hill in sedan chairs to "take the waters" at the Pump Room
• I enjoy the museum in #1 Royal Crescent - a refurbished Georgian townhome. Very interesting!
• Many like the Fashion Museum which you can visit on a combo ticket with the Roman Baths
• Don't spend the money on the Jane Austen Centre. It's expensive for what you get which is a town house where she didn't live and a museum which has nothing original of hers. As mentioned above many enjoy tea there which is not a paid entry.
• Be sure to walk along the river to get the view of Pulteney Bridge (lined with shops). There is a good view from the Parade Gardens which has a paid admission of about 1.50 GBP.
• Many enjoy tea or a meal at the Pump Room which always features in novels set in Bath in Regency times!
  
• There are several museums but not enough time on a day visit to work them in, so I'd skip them and just enjoy the lovely town!

Thank you all for the detailed suggestions! We are so excited!

From the station my order would be Roman Baths, Abbey, view of Poultney Bridge from the south, wander up via The Circus to The Royal Crescent and visit No.1 Royal Crescent.