What is the correct spelling of the word “nightlife” (e.g. social activities in clubs/bars) in British English?
Is it nightlife (one word) or night life (two words)?
The best way to answer these type of questions is to reach for a corpus. Since this particular question is about en-gb the relevant corpus is the British National Corpus, which gives 134 hits for “nightlife” and 42 for “night life”. So either is acceptable, but the single-word version appears to be preferred.