What are the requirements for a small jet type rating in the UK?
As far as I know, you can't get a type rating for a homebuilt jet in the UK. You can do so in the US but you have to find an instructor and examiner rated by the FAA to do that. I would suggest you talk to the manufacturer of the kit about this. They are the most likely to know the answer, but I would not hold out much hope. The UK CAA has historically demonstrated they are not too keen to let people fly homebuilt jets.