Unless the car's been allowed to overheat badly since the headgasket went, you can safely skip that bit.. just check that the surface of the head is not warped by running a feeler guage between a steel ruler and the face of the head - haynes will tell you which feeler guage to use.
Most metal workers will be able to skim it for you.. all the stuff about rebuilding the head is recommended while it's all apart, but not strictly necessary. I managed to do mine in about 2 1/2 hours by cheating and dismantling only what was absolutely necessary to remove the head, as follows:
Unplug HT leads and any electro-trickery on the manifold / throttle body (in my case I had to unplug an inlet manifold heater and two wires from the carburettor, but yours will be slightly different being a mk3)
Remove fuel lines and similar from throttle body - anything connecting it to the rest of the car.
Remove the exhaust clamp that attaches the exhaust manifold to the downpipe
Loosen the camshaft sprocket bolt - easiest way to do this is stick it in gear and use a breaker bar against it, but I'd definately advise replacing the cambelt if you do this, you have to put a lot of strain on it.
Loosen the water pump bolts and turn it anticlockwise as viewed from the timing belt end of the engine. Easiest way to do this is take a breaker bar or similar and a mallet and tap the pump downwards to get it moving. You'll need to give it a fairly solid tap to get it loose, but after that it'll start turning easier.
Remove the cambelt and the cambelt sproket from the head.
Loosen and remove the head bolts in the sequence that haynes manual gives - keep to that sequence or you'll risk warping the head.
The head can now be lifted off along with both manifolds, distributer etc that haynes tells you to remove. It's a good idea to take them off anyway and replace the gaskets, but that's pretty much optional.
Replace everything with new head gasket and head bolts. Do a timing belt and water pump change if you can, it's not worth risking a siezure or a snap and now it's all apart anyway it's a good time to do it
Let me know if there's anything I've missed there.. probably is, but can't think of it.
I really would say that it's not worth spending fortunes having a garage replace it for you, it'll cost you a few quid and a couple of hours to do it yourself, it's not a hard operation
