I must be missing something but I have no access problem to my engine bay cover bolts. They are 10mm bolts on mine - not sure if that is normal or not, but a simple 10mm ratchet spanner has them off in no time with no issues. But I do like the idea of slotting them to make it even quicker!
Nik
Nik, is your F a Mk1?
.....In the 2018 I intend on doing engine checks on a more regular basis....