Get the builder and electrician to install a SWA cable now, allowing for a separate mini consumer unit in an appropriate location to feed the charger. Cable is cheap compared to installation, so go for one size larger cable if it can be fitted. 6mm2 cable will easily support on EV charging at 32A. My understanding is that 4mm2 would do it if the cable doesn't run for any distance embedded in insulation. But is there any chance that you might have two EVs at the address at any time in the future. Get your electrician to advise.
Also install a few shielded, twisted pairs (say Ethernet cable) alongside it to support any communications that may be required, just for future proofing, especially if there may be weak WiFi or mobile signal at the charger.
For the slight extra cost I installed 10mm cable to my garage with 3 cores so not relying on the armour for earthing.
You might well use a local earth for the EVSE in which case two core would be fine. But if you aren't sure I'd go with 3 ... spares are always good. (If you might go 3-phase any time then 4 cores would be even better.)