How about some simple Google searches.
e.g.
Surveillance radar approach - Wikipedia, the free encyclopedia
SRA's are similar in minima to VOR or ADF(what??) approaches. PRA's(or GCA's) take you down to Cat 1 minima usually. On military airfields in particular, GCA controllers can talk you almost touchdown if necessary(but under pilot responsibility). Their 'patter' after the usual minima is 'for info only'.
As a civvy from years back, I was lucky enough to have practiced a few with an ex RAAF instructor; usually to assist controllers maintain currency.
As an added bonus, I was invited to witness a GCI session(totally unrelated to this thread, but what the heck...). It was fascinating to watch with the controllers even knowing the pilot's voices and directing them accordingly on to their targets.