//I know that if he were coming to my house for lessons, piano say, I would have to be dbs checked.
I could just as easily abuse him if I were paying him to garden.//
You wouldn't, actually barry.
It is not obligatory for a music teacher who teaches in his own home to undergo a DBS check. However, it is highly recommended. As an individual, you would only be able to apply for a "basic" DBS certificate. This will show "unspent" convictions only. If you wanted a standard or enhanced check only an employer or regulatory body can make the request. (in the case of a music teacher, the Musicians Union can do this).