The last statistics I have seen were for the USA. Measured on a fatal accidents per 100,000 hrs basis, a night flight for non Instrument Rated PPL's, is approximetely 20 times more likely to result in a fatal accident than a comparable flight during the day. After personal experience flying with 4 pilots who held UK PPL's I did not see that they were better pilots in any significant way, than the US PPL's I have also flown with. Therefore I would suggest that the overall statistical picture would be the same for UK PPL's who fly at night. Personnally I no longer fly single engine aircraft at night and file IFR for every night flight I do in a multiengine aircraft regardless of the reported weather.