Full Sutton has a C150 for hire at 78 quid an hour which must be one of the cheapest around. And as C150 go it's a bit of a hotship (relativly speaking of course).
The cheapest flying I can think of that you can count toward CPL issue is an Evans VP-1. There is a 1/8th share in one at breighton for 500 quid 25 a month and about 20 quid an hour - its on AFORS website.
There is also another one up for sale at I think eddsfield for 3750 ouright purchase.
Happy flying.