Changing the subject somewhat, I have occasionally used Travis Perkins for selected timber and bulk sand etc. There are two branches close to me but prices (even with so-called 'trade discount') are rarely competitive. However, TP has an online site which is open to all and shows clear prices, with free delivery for a purchase of £20+ (Exc VAT).
I need a lightweight moulded door of a particular type for use (as a sliding door) at my son's abode. B&Q does do them (£28 for a single at present, with 10% off for me on Wednesdays) but they are not stocked locally or widely, at least in the 30" width (although the 27" are more readily available - strange). Other sources are significantly dearer and/or inconvenient. By chance, I found the exact item in TP - and on 'special offer' too - at £25.14 delivered (£20.95 + VAT) - so a whole 6p cheaper than best potential B&Q deal. I ordered one yesterday evening and was called by the local branch at 9.30 this morning to arrange delivery: any time Friday or next week. I'm quite impressed; if TP can offer this service, it is likely to get some more business from me. (TP owns Wickes, Toolstation, Benchmarx etc - often with the same items sold by each at wildly differing prices; the door I wanted was stocked at Benchmarx at treble the TP price, and that for 'trade'!)