Too cheap mate, but then again, my business is very different to yours and above your level of understanding.
Personally, I would have charged 400 quid, but then you must decide in the long run where you want to be. Don't forget your overheads and profit margins must be considered. Don't forget, food, while working, is also tax deductable, this also affects your business strategy and pricing mechanism in the long run. In the short term, for those of you still awake, I find the best way to clean these jobs, is with water filled balloons, 25 quid a balloon, depending on the colours.