I can highly recommend Executive Interiors (website: [broken link removed]). I have no connection with them other than being a very happy customer

I got 2 desks, pedestals and chairs from them when I set up my home office over a year ago. The website does not feature all their ranges but they sell proper, sturdy stuff - it's dearer than flatpack stuff from argos, atlantic etc, but that's not proper office furniture - there's no comparison, I found that they were not expensive compared with some other office places.
The customer service from John there is incredible. He could not have been nicer and nothing was too much trouble - I was really impressed and that's hard to do!

It may not be the kind of stuff you're looking for, but if it is, it's definitely worth giving him a call.
Hope this helps,
Janine.