Mr Memory by John Rhodes

Try this, it's a fairly short book:

http://www.amazon.co.uk/dp/B0057XV34W

or

http://www.amazon.com/dp/B0057XV34W

What do a man with no memory, a disease ridden cat along with a beautiful woman, Fate, Degradation, Famine and Hope have in common? The answers, strangely may lie within this story, where the struggle for power, mystical ageless beings and the delights of office party etiquette meet in a headlong car crash of magic, evil versus good and the odd, (very odd in this case) talking beast or two. Dave's mind is an almost blank slate but accompanied by the decaying tramp come wizard Lenny he escapes from hospital on a quest to find answers and possibly get revenge. Who can help him and will he really like the answer once his mind returns to normal?