Have a look
here, they're happy to ship to the UK on a lot of their products, and the price difference even with shipping is good!
They've got Bell Tents from €230, and a
tent similar to a patrol tent for €500 with a tub ground sheet.
If you order off their Dutch language site you get the whole range, whereas if you order off the English bit you only get part of it; there are some distribution disagreements IIRC that stop them doing the whole range via the English section...
Oh, and give me canvas any day over nylon; I've got a big polycotton tent in the UK for use in France; massive difference in temperature, so much cooler than a nylon tent. My swag here in Aus is canvas, all you need to do is make sure it's seasoned (spray it from time to time with the hose and let it dry out) and it's good. So much warmer than a nylon tent and much less condensation inside as well.
Also keep an eye out for Force 10's, although they tend to get snapped up by the uniformed orgs, as they love them and the new ones aren't as good as the 1980's/90's ones (As with so much stuff...)