Not sure about the UK market, but here in the US office furniture and supplies (anything from paper clips and staples to tape to paper etc.) are best bought aftermarket in bulk. By the truck it's around 8%-12.5% of retail depending on the specific item for known quality name brand stuff -- way cheaper than you could get importing from China.
Unfortunately I have no idea if this is a viable plan in the UK.
Threads like this seem to suggest that there is a vast, untapped market for info on bulk buying in countries other than the US. One can find any number of US suppliers, discussion groups and forums and so forth with a bit of Googling, but virtually no 'authority' info sites for Canada, the UK, Oz & Kiwiland etc. to say nothing of the non-English-speaking world.
Maybe Salehoo should branch out to this, or perhaps local members work on country-specific info sites? Might be a nice source of affiliate/ad revenue if nothing else.
"Failure is not when you fall down. Failure is when you don't get back up."