While I hate to disagree with Genghis - the UK market for FIs is not completely saturated at the moment. Companies are still gently looking for newly qualified FIs on the idea that they won't be scooting straight out of the door. Most schools are very aware that any airline pilot coming back to instruction is highly likely to disappear the instant that the bigger and shinier aeroplanes call!
I fly out of White Waltham and their FI course has probably put throughout about 30 FIs over the past year all of whom have jobs in various companies and they seem to be still getting regular calls from schools asking if they have anyone on the course that they can recommend for employment.
Yes, it's not like it was in March 2020 with schools beginning to self-fund or sponsor people to become FIs for them, but not all bad either! In my opinion, your CV will look better with an FI and recent flight experience than someone who just sat back and let everything expire for a year or two (but I'm not an airline recruiter so don't necessarily take my word for it!)