Raymond Feist.

Not quite sure how this goes but there is 'Magician' and there is a part 2 (other book) as well. Originally put out as one long book, I think, and then split into two (as it probably should have been in the first place).

Not sure if you would get into medieval fantasy (knights of the round table kind of stuff where there is some magic etc) - there are a couple good ones about... 'The Mists of Avalon' etc.