I have always found CEF to be very expensive no matter who I was working for or the location , Northants, MK, Oxford , North London.
I use a variety in order below...
Neweys ( Rexel) as they have known me for numerous years and service is good locally.
Denmans
My local independent Midshires, nice people, good prices and services, and they are always ready to match or better any prices from others.
Toolstation (avoid the cheap brands)
Independants
TLC or other online elec wholesalers
Screwfix (very rarely due to quality of some items but are open late)
As a Sole trader myself I still do find it unfair that larger companies get better prices due to number of units sold but thats the way they work I suppose. Also I do find the whole "lets super inflate catalogue prices to show bigger discount" a big con. I don't care about discount....just the end price. I have never believed the 50% off sales...they always have a few Big Sales after inflating prices for a couple of weeks....same year after year.