So, cracked on and got it apart, suspected head gasket issues so rather than tart around I decided to do the lot anyway.
Due a service much?
Head off, all apart, mega clean up operation and sort the 2 broken exhaust studs. Couldnt get them out with the welder, unusually
Got the head in the pillar drill, 2mm pilot hole first, left one fine, right one the MF drill snapped just as it broke through the bottom of the stud leaving me with a broken stud with a broken drill bit stuck flush in the middle
I solemly finished drilling and tapping the other stud
Now the head is in for spark erosion of the stud/broken drill bit - fifty quid I didnt wanna spend but it is what it is.