I dont know your set up but I would go for an apprentice. But go for a maturer one rather than 16-18. Not that there is anything wrong with a 16-18 but it's sounds like its just you and maybe you could benefit from an apprentice as it will only cost you around £100 a week for a full time one. That way they can study their level 2 and 3 with you and after 2 years you might be in a position to offer them a full time job. They will know all your clients and treatments so will be a good employee for your future as they will only know everything you taught them.
Then when they are full time employed after their level 2 and 3 get another apprentice in and soon.......
Contact a local college and meet with them to discussing see what they have to offer.