Originally Posted by Dog250

In my experience, they don't ask for any pcr results when flying a domestic flight that's connecting to an international flight. Although I was flying from Aberdeen to Cyprus via Heathrow.
If they do ask for a pcr test in Inverness then I believe they can still check you to Heathrow and you'll be able to get a pcr there. Although I am not sure what would happen to your ticket to Cape Town. Hopefully someone with more knowledge can chip in.
A passenger ahead of me didn't realise he needed a visa to visit Russia so the check in agent offered to check him in to Heathrow only.

Thanks!