Hello Andy,
Try the link, its approved document H of the Building Regs, should give you most of the info you need. Page 11 gives the clearances from window openings.
http://www.planningportal.gov.uk/uploads/br/BR_PDF_ADH_2002.pdf
Cheers
Chris
Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website. For the best site experience please disable your AdBlocker.