We use some of these as our local suppliers and builders merchants in Swindon, Wiltshire:
https://www.howdens.com/
https://www.jewson.co.uk/branch-locator/branch-details/?Location=swindon&BranchId=183&Distance=1.62
https://www.wickes.co.uk/store/8342
https://www.magnet.co.uk/find-a-showroom/south-west/swindon/contact/
https://www.kellaway.co.uk/branches/swindon/
https://sansums.co.uk/
http://www.sigroofing.co.uk