Thanks for the info Banjo, it is actually one of the front ones that was stuck, all the others were quite easy and had a nice "craack" as I undid them, however, we this this one was destined to snap as it didn't have any give. all the bolts have good looking washers, and I agree the head bolts are different lengths. and as soon as I get it off it'll go to the machining place, I don't wanna dance with death. I'm swapping the head with someone for a worked one so I want to keep it alright.
Cheers again