These are a few sites that you may find useful
Fensa The industry standard for replacement windows and doors
Building regulations
http://www.planningportal.gov.uk/england/professionals/en/1115314110382.html
British Cement Association (BCA)
http://www.bca.org.uk/
British Precast Concrete Federation (BPCF)
http://www.britishprecast.org/
Builders Merchants Federation (BMF)
http://www.bmf.org.uk/
Chartered Institute of Building (CIOB)
http://www.ciob.org.uk/
Concrete Society
http://www.concrete.org.uk/
Confederation of British Industry (CBI)
http://www.cbi.org.uk/home.html
Copper Development Association (CDA)
http://www.cda.org.uk/
Federation Of Master Builders (FMB)
http://www.fmb.org.uk/
Institute of Roofing (IOR)
http://www.instituteofroofing.org.uk/
Lead Development Association
http://www.ldaint.org/
Lead Sheet Association
http://www.leadsheetassociation.org.uk/
National Federation of Builders (NFB)
http://www.builders.org.uk/
National Federation Of Roofing Contractors (NFRC)
http://www.nfrc.co.uk/
Timber Research and Development Association
http://www.tradatechnology.co.uk/