This may be of limited use at this stage but my OH flew in the last few days from NCE to LHR in CE and he got a €20 voucher airside to use at the Starbucks to make up for the lounge closure.
Also, on tests: he had a standard antigen test from a French pharmacy and that was accepted OK for pre-departure test to the UK. I doubt that standards would be different between different French pharmacies.