Rather than going for a 3/4 plate with reduced size font, get standard size letters cut down to an 11mm border round the edge. This is the minimum border required by law but is also noticeably smaller than standard. They may get s**tty if you haven't got the BS number and the postcode of the place they were made on them, but then they were on the car when I got it, officer
Fancyplates may help you.