It can be done, yes. I learnt as an adult at a very informal place, was asked to muck out, tack up etc. Some schools charge for stable management. I was the rider who would get on anything, so I'd get a call asking me to come and ride the horse being driven in on the lorry from a dealer. It was great fun. I now own, but I don't charge my sharer, she's a star, does every morning, is a better rider than me and covers any evenings I can't do. There are ways and means, but it's handy to spend time at a school or yard.
People always want sharers. If you can ride competently and unsupervised and do rugs/make up feeds, then you could easily get a share.