This is usually more of an issue when the dc are little and you can't afford babysitting and are trapped at home with them.
But in your case they are of an age you don't need to worry about that.
It's difficult at the moment with covid as people aren't socialising much at all, but under normal circumstances you could get out and about and meet people at weekends.
What are your hobbies/interests if you have any particular ones?
I see you like films - there are film clubs for particular interests and groups that go to the cinema together
Just basing off things I've done in the past (currently housebound so a bit stuck!):
Walking groups
Choirs
Knitting groups
Volunteering roles (long history of guiding and scouting in my family and it's only been a few years since I stopped being a leader/helper, great fun!)
Gaming clubs/groups - not necessarily "video games" (yes I'm an old duffer!) but board games, card games etc some are geared towards a particular game eg chess or poker, some all kinds of board/card games are played
Creative classes - art, writing, drama
Exercise classes/gym/swimming
If more home based things you're looking for and to include a mix
there are online clubs and groups for all kinds of interests and discussion, I'm on the forums for some of the phone games I play, also music fan groups, film fan groups etc
Reading - I love kindle myself but others prefer real books only
Puzzles - crosswords, sudoku etc
Crafts - knitting, cross stitch, crochet, card making (you could make all your Christmas cards if you start now), painting and drawing, alter/upcycle old clothes and household items (I'm more clothes side, a relative enjoys buying old furniture and doing it up)
Use the time to batch cook/bake
Learn something - a new language, a skill whatever takes your fancy
Plus of course loads of mn'ing! 
Loneliness hits at times as a lone parent are you recently a lone parent? You get used to being alone. I've been single (to all intents and purposes I'm not a saint
) for 18 years and after just a short while to be honest I found I preferred it!
Does that help any?