I've used both Digital rev and hdew cameras without problems. Digital rev was for my 7D, 24-105 and 12-24 all in one package. It was shipped to me via DHL direct from Hong Kong and on the outside was marked as being worth about £30-£40 to avoided customs opening it, actual value was more like £1600! I bought my 70-200 from hdew and from the box it seems like they shipped it from their UK address.
You could ring them up to settle any questions you have, I did that with hdew. Hdew emailed me to confirm order, that payment had been taken and when it was dispatched so I'd know it would be delivered the next day which was a nice touch I thought.
I'd use both again, by my calculations I've saved about £1k over anything a camera store in the UK could offer.
If you are will having concerns, look up Ian Kerso in Scotland. He seems to be well recommended (although I haven't used him myself), and I think he may actually be selling items with a UK Canon warranty, which the others I have used don't offer, they do provide their own warranties though.