My wife has her PR card, we were officially landed in Feb 2006. What is the maximin time she can leave Canada and then return without loosing her PR Status.

Basically she needs to go back to the UK for a year, would this be a problem
when she trys to re enter Canada

A year is no problem. You must be in canada for two years total out of a running total of five years to keep PR status, although there are also some exceptions (posted overseas by canadian employer, overseas with canadian spouse are two)