...I think I need to look at more of his work. Whilst on this topic, am I the only one on here that hasn't got a Scooby about any famous togs, I'd struggle to name any and have already forgotten the judges from the previous episodes
Depends what type of photography you like, but I'd suggest the following as a starting point:
Landscape: Ansel Adams is the obvious contender and he made some great images. My personal favourite is John Sexton (he worked as Adams' assistant for years). Colin Prior is also worth checking out - he does regular talks.
Portraiture: Norman Parkinson, Annie Leibowitz, David Hearn, David Bailey, Terry Sullivan, Yousuf Karsh, Chalky Davies.
Documentary: Henri Cartier-Bresson is the obvious choice, but I prefer Brassai's work. I find HCB a little "safe" at times, and Salgado, of course.
Wildlife: Andy Rouse is excellent - gives lots of talks and worth seeking out.
For something a little (well, in some cases, very) different I like (some of) the work of people like Weegee, Joel-Peter Witkin, Sally Mann, Diane Arbus, Robert Mapplethorpe (made some superb still-lifes of flowers and some very challenging homo-erotic work - not for those of a nervous disposition).
IMO you could do worse than look at the work of almost anyone who's worked for Magnum.
One final point - books and the interweb a great but there's no substitute for going to an exhibition of real photos in a gallery.