am i right in thinking that a sunroof from a mk2 will fit my mk1? 
also need to make my mind up on what route to take for the car, full resto, fully custom, just light mods 
Yes mate, a factory fitted MK1 sunroof is the same as a MK2.
only you can decide what you want to do.... heres a few things to consider, do you intend to keep the colour? Do you intent to keep the engine?... its a 5 door so only light mods would work IMO. If it were me it would be old skool look all the way with it.