Hi there, wigtv2000 - as others have mentioned, the moving curtain means there's virtually no chance of you not being allocated a seat in the 'Club Europe' cabin as booked.
As a newcomer (from your remarks) to BA, you should prepare yourself to be thoroughly underwhelmed by this first experience of their shorthaul business class. With seat pitch (and seat itself) same as economy, you have to hope that the person in front doesn't recline their seat. You'll be given something to eat & drink, but little point paying to select a specific seat.
The LHR-CDG sector was clearly booked as part of your main transatlantic trip ; but when booking intra-europe shorthauls as a standalone, the sweet spot for many savvy BA regulars is to go for an exit row in economy class ('euro traveller' in BA speak) where you'll enjoy more leg-room than in business.
All that said, for such a very short hop there's really little to worry about.
Oh and welcome to the Forum^ You may well receive an 'official' welcome shortly (and probably with a more positive spin on BA's business class shorthaul than my own ......)