If you have lived together at the same address for 2 years and can prove it he can apply for the Unmarried Partner visa. If not you will need to get married and he can apply for the Spouse visa. You will need to be able to sponsor him - see
https://www.gov.uk/remain-in-uk-family/overview
Alternately, he could apply for a student visa if he wants to study full time and can afford all the fees.
Work visas are difficult to come by but a spouse visa allows him to work anyway.