Some general figures for a simple aeroplane like the 172:
Fixed costs:
Insurance: £2000 per year
Hangar: £2000 per year
Annual: £1000 per year
Star Annual (extra allowance per year): £700
Repairs and spares: £1000 per year
Total: £6700 pa
Based upon 200 hours per year gives: £33.50 per hour
Now the running costs:
Fuel: £40 per hour
Engine fund (£20,000/2000): £10 per hour
Extras (oil etc...): £5 per hour
So your total real running costs if you do 200 hours per year is: £88.50 per hour inclusive of pretty much all costs EXCEPT unforseen costs exceeding £1000 per year.
Pretty rough figures but seem about right in my experience. Most simple SEPs will be about the same (unless permit or µlight)