Hi
In hampshire youve got south coast cqb in portsmouth and ironsight airsoft that do summer night games on thursdays. UCAP also do mid week games at The Bunker in portsmouth i think on tuesdays.
Near London Splatoon (essex) had started to do saturday night games, and I think Apocalypse Airsoft in Kent had some planned on Fridays. Mayhem (romford) also did night games on saturday. Legion airsoft also do milsims at longmoor camp in hampshire.
Hope this helps and im keen to know of more.