ooh im trying to get into it myself. Here is what i have got from Learn Direct. Its quicker to pay for the qualifications rather than going to college which takes longer, but if you dont want to get qualified (you shoul das it enhances your emplyment prospects) then you can do assistant fitness intstructing instead.
Doing a course which enables you to gain entry on the Register of Exercise Professionals (REPs), which is also known as the 'Exercise Register' will improve your chances of employment.
REPs has been set up to help safeguard the health and interests of people who are using the services of exercise and fitness instructors, teachers and trainers. The Register recognises industry-based qualifications and practical competency, and requires fitness professionals to work within a Code of Practice.
Any of the following Level 2 VQ) will give full entry to the REPS:
Central YMCA Qualifications (CYQ) Certificate in Fitness Instructing (gym, exercise to music and aqua)
OCR Certificate in Teaching Exercise and Fitness (exercise to music, gym, and aqua)
Active IQ Certificate in Gym Instructing.
I have applied to Lewisham college to do the course leading to the YMCA course, there are three levels, 1,2, and 3 (3 enabling you to register as a personal trainer)
Hope this helps