I think that you are going to have to provide a little more information before you get definitive answers.
Where will the aircraft live? If its parked at an airfield around London you are looking at about £300/month for hangarage, £150 for outside parking. If its living outside - add on £500+ for a cover.
Insurance - you'll have to ring for a quote, it depends on the value of the aircraft & your experience.
Engine fund - depends on the engine hours, but you need to be away that sooner or later, even if you keep it going on condition, your engine will need replacing - £12K. There comes a time when the cost of continually patching up the engine is starting to equal that of a new one.
50hour checks - The more you fly, the more of them you get.
Annuals - doesn't matter how little you fly, you still get one! The older the aircraft, the more they cost. We paid £2K on a 5 yr old a/c.
Fuel is about £1.25ish per litre, you could be burning about 6g/hr in an average C150.
The cheaper the aircraft you buy, the older its likely to be and the more it will cost to run.
"If you want to make a small fortune in aviation, start with a large one"
As Fitcom said, there are other ways to go hour-building,.