Head gasket.

My 2003 Avant B6 SE 2.4 petrol V6 developed a misfire and, after a visit to a mechanic, the computer said there was a problem with cylinder 5 and, after closer examination, the problem was diagnosed as a leaking head gasket. 150,000 miles on the clock but the engine ran as smooth as anything until the misfire.

The car has sat on my driveway for months as I thought that I might undertake the repair myself as an outdoor project (summer when it's hopefully drier and def warmer).

I did stick some "gasket sealer" in as a last ditch (car was orig going to be scrapped) effort and I do really like the car and then decided I couldn't part with it yet, after all.

Other problems:-
Front dampers need replacing.
Inside head lining has come unglued.
CVT in reverse can be lumpy.
Plastic headlight mounts/surrounds brittle and one broke.
Car is old.

I am anxious that the head might need 'machining' and I won't know if it does.

My questions and reason for posting this?
Am I being stupid?
Is it 'doable' for a 'home DIY er' outside.
Obviously the timing belt (and sundries) and water pump will also be replaced so it's not going to be cheap.

Any advice or "I've done this" or "don't bother" advice would be gratefully received. I suppose I could buy another.

I really miss my V6 (even if expensive to run).