You would struggle to get cheap flying out of the aircraft you have listed - they have a high capital cost which not only makes them expensive to buy but also expensive to insure - which in most cases will significantly outweigh the lower running costs.
To find a low-cost group you would probably be looking at an older aircraft with low performance operating on a permit. I recently found several in my local area in the £50 to £70 a month / £50 to £70 per hour bracket. Not South East, but not far away.