Make sure you have another manifold in good nick with new studs fitted or at least ones in good condition. Removing the manifold is a fiddley-arsed operation at best, requiring sockets and extentions that need to nearly to accomplish a figure of 8!!
That said, it is a job that most DIY'ers can do themselves, but it is a pain. Quicker and easier IMHO to supply a decent manifold as said earlier and approach a garage. If you have all the spare parts, the garage have little or no comeback as to why things take so long!!!
If they say, 'sorry mate, the head has to come off to change the manifold', walk away. The only reason the head may have to come off is to remove an 'impossible to get at,' broken stud.
