Is advance booking of train tickets advisable in France?

Book that one in advance.
What exact day are you traveling to Bayeux so the people here can look it up?

Traveling to Bayeux on Wednesday May 7 and then on to Angers Monday May 12.

I looked up both and I would book them today
https://www.sncf-connect.com/en-en

We just returned from France, with a lot of train travel. I used the SNCF app, and had an easier time with the Trainline app.

So here’s another option for you, if needed. I kept both apps on my phone for our trip, but the Trainline one worked best for our advance purchases.

https://www.thetrainline.com/

Good luck!

Laurie

French train tix go on sale four months in advance. If you buy your tix now online, you can pay as little as $36 for Paris to Bayeaux, and $51 for Bayeaux to Angers. However, as those least expensive tix get bought up, you could be looking at $120 for the Bayeaux to Angers trip.
There reportedly is no mark-up in train ticket prices sold by The Trainline above what SNCF sells them for, according to Mark Smith, “The Man In Seat 61.”
www.TheTrainline.com. The Trainline is contracted with SNCF to sell its French train tix and makes most of its profits from advertising.
www.SNCF-connect.com

Thank you to both Laurie and Kenko for your good advice. I did go online and purchase the tickets. I got good prices but in one instance had to pick a train leaving at 7 am to do so. I will go to the trainline app next time; the official SCNF (?) app was a royal pain to use....

The official SNCF app is bad. That is the reason why Trainline exists, as it was created by a group of programmers frustrated with the SNCF. There is another app called 1.2.train -> https://www.12train.com/
This reduces the whole ticket purchasing process to the essentials.

Note that while booking in advance gives you a discount it is not needed on this route, as there are enough train on this route. For example: If you were to walk to st. Lazare now, and buy a ticket for the next train you would be on the 8:29, for a cost of 54.20
Booking in advance gives you a discount, but not a huge one.

And don't book to far in advance. You may end up in a situation where you try to book at a time when not all trains are on the schedule yet, resulting in you picking an unsuitable departure.

That is the reason why Trainline exists, as it was created by a group of programmers frustrated with the SNCF.

Trainline existed before that. You must be referring to Captain Train. Used them years ago when I found that purchasing from SNCF was impossible due to 2 factor identification requirement on credit card transactions. Prices were exactly the same as on SNCF, with no added fees. Then, as often happens, these programmers cashed in by selling Captain Train to Trainline.

Millions use the SNCF site every year. I would work it out before i put someone else between me and the vendor of the ticket (trainline or anyone). Just no reason to ..... Maybe its just the principal of it. Maybe I am overly cautious in a situation where there is zero return (other than can I use a website that millions also use). But it works for me.

Thanks for your thoughtful replies. A large part of the difficulty with SNCF was the two-factor authentification requirement. I will get the Trainline app for future use while in Europe.

I have been advised to use FAIRTIC in Switzerland (in fact it is a requirement for using the free travel on the tourist card in Neuchatel as of 2025). Any comments on using FAIRTIC elsewhere in Europe? Does it work in France?

I have never heard of FAIRTIC

What is FAIRTIC and who advised it?

A large part of the difficulty with SNCF was the two-factor
authentification requirement.

I thought that was something you set up with your bank. I didn't know a vendor could imposed it on you. Interesting, live and learn. Wasnt a problem for me with the Austrian, German, Hungarian or Romanisn rail companies.

Sorry, I misspelled it. Should be FAIRTIQ. Here is what the Neuchatel tourist card instructions say: "To use the NTC-Transport and travel for free within the canton of Neuchâtel, you need to install the FAIRTIQ app and enter a promotional code (PromoCode) generated in your NTC web app." Before this year, you would get a tourist card from your hotel that gave you free admission to all the museums in the canton, free transit, etc. Now apparently the hotel is to send you an email three days before you arrive, giving you the link to the tourist card app which you install on your phone.

And here is the FAIRTIQ website: https://fairtiq.com/en/

I never heard of FAIRTIQ before this year so have no knowledge other than what I read online.

WengenK mentioned it a few weeks ago. A new wrinkle.

You must be referring to Captain Train.

That is exactly who I was referring to. Capitaine Train was then bought and rebranded by Trainline.

FAIRTIQ is a Swiss product, that allows you to do pay-as-you go in the same way as eg the OVPay in the Netherlands, or the Oyster Card in London, but without needing any infrastructure, as it is all done on your phone.

So you load the app, add your credit card, and then you "check in" before you start your trip,. and "check out" afterwards. The app will track what you are doing and charge you for the rides you took. It is able to take in to account any passes you have if you enter them and so will only charge you for your travels outside that area.

It exists as a standalone app, but also has been integrated in the SBB app (where it is called "easy ride"). And other areas on Europe are introducing it as well. You can learn more here:
https://fairtiq.com/en/

It is a way for public transport providers to offer "tap and go" functionality, but without having to install expensive infrastructure. For the OP: It appears to be used on some routes in Normandy as well:
https://support.fairtiq.com/hc/en-us/articles/19442044736530--FAIRTIQ-in-Normandy-Overview