Going to use Loctite 518 to put the two halves of the head back together.

Just wondering if the sealant goes on all flat surfaces (including head bolt hole surfaces) or just around the outside?

RAVE shows where to put the sealant. Ideally use a roller.
Dont use too much, you dont want to block the oil ways that feed the cam.
Looking at the spec I guess Loctite 518 is a suitable alternative to the Hylomar RAVE says to use, probably cheaper, the Hylomar is about £45!
Mark