There has long been a story going around that women outnumber men in Nottingham by a large amount - 2 to 1 in some reports - but this is a myth. In fact there are about 2000 more women than men in Nottingham but this is not unusual for the UK. Some think the story may have started back in the days when women came to Nottingham in large numbers to work in the lace factories, and it is being kept alive now by the organisers of stag nights.
The Office for National Statistics has population figures for each UK city divided by gender, but not an actual indication of which town has the highest female to male ratio. However, if you go to their website you may find more information which can help you.

Overall the UK has slightly more men than women, but the figures in most towns are almost even.