The basic blue disposable surgical masks are on sale everywhere here. There was a bit of price gouging going on when lockdown started but you can buy packs of 10 for a couple of quid in most corner shops now. I have never used them because I don’t like the way they end up in landfill.
Most people (of the people who wear masks) have cotton reusable ones, with fancy patterns. Seems like it’s almost a fashion thing. My wife (who has a biggish Instagram account) has been sent a bunch of them by local fashion designers. They all look fecking stupid. I refuse to wear them. Luckily work sent me some basic white cotton ones, which do the job. Youtube is full of videos about how to make your own from bandanas, socks etc