Flat Oot like a ducks Foot
Head gasket not a big deal if you do a bit of spannering.
Just make sure you get the timing set up properly afterwards when you put it back together. (Or a locking kit)
Obviously you will likely get a bit of water oil mix, so give it a quick run afterwards & an oil change after that.
If it all sounds too expensive & complicated, chuck in some rad weld & carry on...
Would you believe a mate of mine has run his 2.0tdi like that for over a year?
I think he's in for a shock at some point...