Import of a kit aircraft from the USA is strongly cautioned against by the LAA, who, depending on the aircraft type (which would have to be one of their approved designs with no unapproved mods in any event) may require substantial dissasembly in order to inspect parts than can only be inspected during the build process.
If you have a particular type in mind, an easier option would be to find a UK-built example. Suggest you have a look at the classified ads on the LAA site.