In the meter the main cut out fuse has indeed got 100 amp written on the blue sticker on the side of it – BUT – someone has put a white sticker on the top that says 80 amp!
The cut out carrier (fuse holder) is likely rated at 100A with an 80A cut out fitted.
Your home at 5yrs old is borderline being wired to the the latest 18th edition wiring regs or at least to the 17th edition cover all the latest amendmants. Either way your home will be fine where fitting a charge pint is concerned. If the cut out rating needs upgrading it will be carried out FOC by your DNO, so why waste money having an electrician to check and not all electricians are allowed to touch it.
As a sparky or over 40yrs and qualified EVCP installer you’d be surprised whats what. I also wouldn’t be going fretting on having a charger fitted to a house thats only 5 years old either.