hi there
are you asking this question because you have ajob to quote, or are you asking this question so that you can fill in the gaps in your price list ??
if it is the latter may i suggest that an others price may not be the price that you either need to charge or could charge, dependant upon your overheads, wage rates and local competition.
if it is the former then i assume that you have done a site survey, and therefore at that point you have calculated the amount of time that it will take for you to do the work,
therefore
hours x hrly rate + NI + materials at 3% of total labour + overheads + required nett profit percentage ( anything from 5% to 20% ) = charge to client.
regards
martin