work out how long you think it should take, you may want to do this in sections ie front of flat 1.5 hours back 1 hour 2x sides 45mins each is 1.5 hour, total 4hours £20 per hour would be £80 if you are wfp price as trad so 4 hours trad may take you 2 to 2.5 hours if it takes 2 thats £40 per hour hope this helps dont sell your self short just to get the job better to have work priced well that you enjoy doing than lots of under priced work that you dont enjoy doing marc.