No loopholes at all, you can't even pay somebody to build it for you. Some countries have ways around this but, it's one of the peculiarities of the UK that we have the highest standards of safety in the world, and the lowest standards of what we can then do with our aeroplanes. Frustrating, but there you go.
You couldn't even readily go to a company like Britten-Norman or Slingsby who can build their own aeroplanes, because the CAA would take the view that the type's design hadn't been investigated to CofA standards and only to permit standards. Your best bet would be to try and bring in a CofA aircraft from, say, the US, and deal with CAA on the design approval side - but that'll be far from straightforward either.
G