Changed the 12mm adaptors to standard QR and the freehub/cassette just slips off easily. Normal? When tightened up it should be all ok but is this normal?!

Ive lock nutted the cassette right (checked)

Check that you got the plastic seal seated properly when you put the free hub body back on. There are a number of folk who fall foul of that, me included.
http://singletrackworld.com/forum/topic/hope-freehub-puzzler

Yeah as above hora mate
Hope say you need a special tool but you don’t just take the cassette off and press down the black ring seal into the hub body just make sure it’s on the tight way up and seated in the groove on the freehub body

Nothing extra or missing. Theres a metallish spacer at the foot/around the axle with freehub removed. Give up. Got a old pro2/dtswiss thatll use for now.

Ive got to try and remove a seatpost shim thats jammed stuck. No remove no ride this weekend!

Which numbered item is it that needs repressing in?

http://www.roteccycles.co.uk/ekmps/shops/rotec/images/hope-pro-2-evo-10mm-through-rear-conversion-kit-%5B2%5D-2317-p.jpg

Seal fitting is at 5:10. ?I don’t have the special tool but found a 40mm plumbing fitting that is exactly the right size. Only the seal holds the freehub in place until the skewer is tightened.

40mm plumbing fitting- look for a cylinder 40mm wide in b&q?

Would a block of wood/hammer work?

If the seal is worn it won’t click in. I think it is £2 but no particular consequence of not replacing it imo.

The wheel itself is less than 6months old

Seal fitting is at 5:10. ?I don’t have the special tool but found a 40mm plumbing fitting that is exactly the right size. Only the seal holds the freehub in place until the skewer is tightened.

You can get a Hope tool, it comes in the kit for replacing bearings, and it works very well.

Or separately:

http://www.chainreactioncycles.com/hope-pro-2-seal-tool/rp-prod28390?utm_source=Google&utm_medium=Shopping&utm_name=UnitedKingdom&gclid=CIXriZX8vr4CFdShtAodHGYAIw&gclsrc=aw.ds

As mentioned, sounds like the seal is either worn or has popped out.

I never needed the tool, the seal went back in by hand once greased.

I pulled the freehub off by accident when trying to pull the old qr adaptors off and ended up with the whole freehub assembly in my hand!