Right so I’ve found the problem, and apparently it’s fairly common, the exhaust manifold has come loose, the rasp kind of noise is the gasket fluttering.

i nipped them up with a 1/4 ratchet but one has snapped 😂🤦🏻‍♂️ I managed to get another nut on the couple of threads that are left and only done it up slightly just to stop it from moving too much, bit stupid I know as I currently have a fair bit of stud to purchase on for removal 🤣

ill have to get a new gasket/stud/nut kit and replace them, it was freezing so I’ll wait a bit longer and hopefully with a hot engine I can get the studs out without chewing the threads on the head 😬