I wouldn't worry Christine. It is the frame number, the VIN, that the customs look at.
But if you are really concerned there is another piece of paper work you could bring along - it's called something like the" international certificate of vehicle ownership" (check the paperwork section of this site for exact name).
It is a small booklet with lots of translations of your essential details, including engine number I think. I believe they are available from the AA - or RAC perhaps.
Around the world 2000-2004, on a 1993 Honda Transalp