About to put in rear wheel when i realise i havent put the new chain on DOH !!!.

There's a sentence like this in any description of a procedure you've only done zero times before :-)

Here's one from me:

Blown headgasket in 1973 Innocenti Mini Cooper, apply torque wrench to 11 head stud nuts, remove carburetters, exhaust manifold, various hoses. Attempt to lift head off block - won't move, pull harder, still won't move. Apply engine hoist technology and heave.... slowly... rises... up... POP! - off comes the head which has suddenly become free because I've overcome the tensile strength of the thermostat bypass hose which is cunningly hidden (and was still connected) under the thermostat housing.

So, head now off, gasket scraped off, typical Mini head de-coking (black and decker with wire brush accessory). New gasket, head on, carburetters on, exhaust manifold on, apply torque wrench to 11 head stub nuts in *just* the right order. Done.

... or rather, not done. Have forgotten to replace the thermostat bypass hose and need to start all over again (using another new copper/ally head gasket - once they're squished, they're squished).

--
simon