Why not just buy a JDM that is already in the UK, preferably one that is privately for sale..and then hopefully it will be fully sorted ,probably with a few nice goodies fitted..Then you will have no worries about waiting months for a car to arrive with no guarantee of condition or worse putting your money with one of the importers who may go bust in the meantime
There's simply loads of good cars for sale at present at very cheap prices, I personally would never give someone my money upfront and then wait months for a secondhand car to arrive...Also if you see a car advertised privately there is also scope for negotiation as to the price..