UK train tickets

Yes that’s about right. Trains are expensive. An off peak return is about £65 but at peak times the fares are much more. This is a popular commuter route and on top of that a lot of people travelling peak are business travellers who have the company pick up the tab.

I have not been able to get a cheap advance fair on this route in years but it may be that it is possible at some off peak times.

You can reduce the price of off peak trains by a third if you qualify for any of the railcards.

If you leave Paddington after 9.30am on a weekday after and buy a flexible Off Peak Return it is £104.70.
If you leave after 10.30am on a weekday or anytime on a weekend a Super Off Peak Return is £75.90.
However there is a cheaper way to Bath, leaving from London Waterloo and changing at Salisbury. Booking Advance tickets on specific trains that is as low as £21 each way, more typically £30 each way. Even leaving London very early .

But you could book that to give a two city itinerary - Bath then Salisbury for evensong at the Cathedral.

That is before any railcard discounts you may be entitled to, say senior (over 60).

If you are going to be doing several day trips from London you could look into a Britrail London Plus pass (which you buy at home before travelling).
If you are going further afield then a Britrail England or UK Pass.
The passes are very good value for money. For instance next week I will have the domestic version of a Britrail UK Pass (a lot more expensive than Britrail). On Monday I am travelling from the Lake District to Penzance with a stop for sightseeing then Evensong at Exeter Cathedral for a per day equivalent cost of £65 first class and haven't purchased anything yet. On Britrail the same journey would effectively cost about £45.

There is also something called the Great West Way Discovery rail pass- £299 for 7 days. As many journeys as you like in a week from London Paddington to Bristol direct via Bath or from Waterloo via Salisbury (from London after 9.20am on weekdays). It includes the Bristol airport to Bath or Bristol buses, many other local bus routes, and all Thames Valley branch lines including Windsor.
That can be purchased on demand.
There is a lower priced East version of the pass (valid as far West as Swindon) which includes the Oxford HoHo bus, and discounts on the Heathrow to Reading and Oxford express buses

The international version of the Great West Way Discovery pass has no time restrictions so can be used on peak time services. It has to be bought from outside of the UK.

If you're planning on multiple train trips, you could consider a Brit Rail pass. The pass allows unlimited train journeys during a certain time period. (eg, any 4 days within a month). There are different passes for different regions, from covering only London and the surrounding area, to all of England, to the entirety of the UK.

They're not cheap, but if you're planning on taking several longish journeys, a pass could potentially offer some savings. They also offer flexibility - you can board any train, at any time. This might appeal if you like to get away early in the morning, at peak travel times (which could be an expensive ticket).

You would have to buy the pass before your trip, and they're only sold to those who live outside the UK.

This may or may not be suitable for your trip, but just something to consider.

Thank you everyone for confirming that I wasn’t doing anything wrong with the train ticket pricing. I’m still pretty astonished by how expensive it is. These prices make a day trip from London to Bath feel pretty impractical. I’ll likely look into driving instead, as public transportation at these rates just isn’t justifiable.

For a day trip, I would not recommend driving. The train is so much faster.

It is typically £4 one way on Flixbus even quite close to the day of travel. National Express is another alternative with more coaches and better timings but higher prices.

Driving from London will be a pain. If I’m going to drive (going from near Bath to London) I leave super early to avoid traffic, park at a station in London transport zone 5 and get a train for the last part of the journey.

I agree the train is expensive and a lot of people take the National Express bus instead to save money, or drive and park somewhere with transport links. The train so much nicer and quicker though.

I agree that train fares in Britain are far too high. I have driven the M4 (the ‘Interstate’ that you would be on for most of the trip) and I can assure you that it is not exactly relaxing due the sheer amount of traffic - even when you are out in the countryside. I have never been to California but have seen plenty of footage about your congested highways which leads me to think that you certainly need that new high speed railway linking LA & SF.

Most Brits would not dream of driving into London and the majority would use the trains. When you come off the M4, you then have the awful A46 for the final few miles into Bath and that is not fun either. When I have driven to Bath (because I needed the car to go somewhere remote afterwards), I have used the Lansdown Park & Ride on the northern edge of Bath. A P&R is where you park the car for free and pay about £4 for the return shuttle bus down the very steep hill into Bath.

So, you are visiting in late August and I note that the cheaper advance fares are not yet loaded on the ticketing websites - but will be in say 2 or 3 weeks time. If you can, I suggest that you try and do the trip on a Saturday as the high rate peak fares don’t apply on weekends. The train company is GWR but Americans have had trouble paying via their site so I suggest you could try this one:> https://beta.trainsplit.com

I just checked for Saturday 2 August and found I could depart London (Paddington) at 8am for Bath and if I returned on the 16.00 from Bath, the price (without a Railcard discount) would be £55.50 return - which is more reasonable though still not exactly cheap. Note that these Advance’ fares are for specific trains and prices for these tickets rise in time. Other trains are available for slightly more.

The journey takes about 1 hour 20 minutes travelling at or near 125mph most of the way. Here is video of the trip.

Have you priced National Express Coach?