Cotton swimwear

Due to a condition I have I have become allergic to pretty much every material other than cotton. This has left me pretty stumped on what to do this summer for swimwear. I can tolerate some elastane/spandex, I have 5-10% in my underwear and bras. I have seen some 100% cotton swimwear but I just also feel it would become so uncomfy and heavy after getting wet? I wonder if there is anything that’s a cotton/spandex mix to give it a bit more stretch and leeway? Any suggestions would be so so so appreciated. I’m UK based at the moment so something that could ship here, even if it’s from abroad! Thank you so much.