Generally I'm happy buying from Screwfix for electrical and plumbing but whilst BES act as an alternative for plumbing, I don't know the best (non-trade) alternative for electrical supplies. There are always a few things Screwfix don't sell, and of course "Screwfix" and "special order" don't mix well.
Current problem is the consumer unit. I want to buy an MK 21 module unit, but presumably nobody else does so screwfix don't stock it.
Fash
CEF
Toolstation do some MK stuff
You can go to electrical wholesalers such as Newey and Eyre or WF Electrical for these. They may not have stock but can usually get for next day delivery.
Don't worry about the "trade" aspect. They will happily take your money.
MK has highish list prices but expectation of discount, so do ask. If you can't get discount at least equivalent to the VAT, you are not trying hard enough :-)
TLC -
TLC
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