firstly you are entering a highly competitive market, is it solely going to be website based?

you really need to speak to the likes of mahle, NGK, Comma etc and find there uk distributor. You will probably find that the manufacturers only sell to authorised distributors, so you will have to contact them.

people like camberley auto factors for example sell millions and millions of pounds worth every year, so i think you will find it hard to compete - especially as if it is going to be website based, people who will want to buy, filter, plugs, oil, pads, discs will want it on the same day and not have to wait. - i know i do.

i presume you are going to do some sort of SEO on keywords to generate traffic to your website? do you intend to offer inventory or are you going to dropship?