No.
There are rules about the type of glass that may be used (and a requirement for good visibility) if a windscreen is fitted. There are also rules about windscreen and wipers and washers but they don't apply to vehicles with no windscreens (or windscreens that, for example, are so low that the driver can see over the top anyway):
" . . .every vehicle fitted with a windscreen shall, unless the driver can obtain an adequate view to the front of the vehicle without looking through the windscreen . . ."
http://www.legislation.gov.uk/uksi/1986/1078/contents/made