If you,don't have tinder / a smart phone with apps -

[Aridane]

and are above the age of clubs, alcohol and drunken encounters,many want a NSA encounter safely (enough),'where do you go?

[Mildinsanity]

swingers clubs personally... well not now but in the past, theres a few in the UK which Id recommend for single women that I know are safe and very friendly.

[TheNaze73]

Over 40's nights/soul nights etc, attract a nice crowd of people who want the same sort of thing. Watch out for the creepy married ones though

[HandsomeGroomGiveHerRoom]

If you're on MN, you can get on to OLD sites like Plenty of Fish. Just specify no ties. I kind of did that, but ended up engaged to the first man I met with