I do not know if that model was ever offered in the UK, it’s unfortunately not listed on http://www.chinesemotorcyclepartsonl...rers_Lifan.php
I suspect that bike is about 120kg, not particularly heavy, so “our combined weight” would be a bit more then 270lbs.
I think you would need to take the fork apart and then see what size the seals are?
http://www.china-parts.co.uk/acatalog/Fork_Seals.html
These people sell the fork, they may be able to tell you what size the seal is?
http://www.hooperimports.com/product...200GY-2-P09-12
another long shot would be this one time dealer for Lifan in the USA, you only need to know the size of the fork seal for the USD type fork on a LF200GY-5, if in fact that is the bike you have.