Exceptionally (because they are beyond awful to deal with if you get any problem) make life easy for yourself and get yourself a 2 euros a month sans engagement SIM contract with Free.fr to get a French phone number.
If Orange is the only game in town with a signal near your place sosh.fr (the LCC of Orange) does the same for 5 euros. That will give you a French phone number.
The reason I suggest this is Leclerc app, which they’ve basically switched to as the only place they’ll allow loyal customers to save quite a few of the discount coupons given to them, is geolocked. It won’t download to a phone with a French contract SiM in it, in France, if the phone is not also set to France market (this is deep in phone settings and can’t always be changed by the user).
So the Leclerc app is set not to allow Playstore to download it due this quite extraordinary level of geolocking. Because it wouldn’t download to UK hardware even when the UK was in the EU, and I believe it’s also refusing to download to other EU countries like Czechoslovakia, or Germany, which IIRC is illegal discrimination in offering services amongst EU citizens.
I raised a complaint about it as a longstanding loyal customer when they switched so many new discounts to app only and mentioned the probable illegality but I got “Le Shrug”.
So do yourself a favour and don’t try to beat it just get a French SIM. If you’re in the UK a lot you might want to consider if you need to pay slightly more so that your French SIM could receive calls whilst roaming in the UK, in which case if Bouygues signal is good at your place take a look at their sans engagement packages too.