Start by googling beauty therapy courses in your area. Then contact the admissions staff to find out more about the courses they offer. Course fees vary between colleges for both part time and full time courses, so make sure you know that exactly what it costs inc. uniform and equipment fees.
If possible, book a couple of treatments at the college salon to get a feel for how well it's run regarding teaching provision and whether the students enjoy being there.
You'll need to complete the equivalent to a City & Guilds (or VTCT) level 2 as a minimum to get employment and most salons prefer staff to have completed or be studying for level 3.
