You could even offer a next day service if royal mail registered post is used by both parties and as long as nothing on the car is broken/snapped that you cant replace from your LHS. Luckly as your in london that should help.
You gotta look at it in terms of the time you spend determins the cost.
Eg bronze service takes an hour =£7, silver 2 hours £14, gold 3 hours £20 etc
Anyway Im giving myself business ideas here so Ill leave you to it
