i did a search and couldn't find anything about a guide to change Alternator Belt, In fact I bought both for my 2001 1.5 Lx with the air con option belt, can anyone help me with the correct procedure for changing belt please.

Such as which nuts etc specifically to undo etc

Here you go, it's basically the same as most normal cars loosen the tensioner bolt, also the pivot bolts and swing the unit in, reverse to tighten it up. I trust you bought a good quality belt, unlike the garage which did this job for me as part of the cam belt, the alternator belt was slipping this morning when I turned on the HRW and fan!