Sometimes its easier to buy rather than build 
Several people in the USA make CM108 based radio interfaces.
Not in any preferred order:
- Allscan Communications: allscan.info
- Masters Communications: RA Series Radio Adapter Index Page
- Hotspot Radios: ARiUSB5
- Toads Digital Interface: TOADs Digital Interface – Temporarily Offline.
The big question would be what are the duties and taxes to be added on top in order to ship to the UK. You'd probably have to contact each vendor and find out. They also might have a dealer in the UK who can sell to you directly.
Steve
WA6ZFT