You don't need an FAA ticket to fly an n erg in the UK. If you are going to the US to fly then it is simple enough to get a new one which will be free apart from CAA fees. If you are just badge collecting it will be very very expensive to get a new one at European DPE rates.....
So ask yourself what it is for? Do you need one or just want one? If it is want then get a full FAA PPL. If it is a need then get a full FAA PPL and don't build a house if cards again.....