I trained there and thought it was brilliant.
The sales stuff is over the top and not 100% honest (as indicated by previous posts). I'm one of the few (there are others on the forum who've been as successful) who went on to being self employed since the course.
I feel I had a different attitude. I researched first of all by looking in the phone book for the number of plumbers in the area (not many around my parts). What made my decision was before I became a plumber I called 18 of the locals to do a day's job the next week. 16 never phoned back, one said he could but would prefer to do it the week after and I used the cowboy who charged £400 for the day and left me with a wonky HTR, unlevel first fix for a shower and a non soldered joint. I could have done better.
I walked into great jobs for my first couple of months then picked up a five bathroom job. Cleared my costs about six months later. Then it went quiet. Really quiet. Odd tap here and there, a radiator move and stuff like that for another six months or so. Then, best of all, I met a plumber who wanted some help but didn't want to train me on how to solder or the difference between hot and cold water. He taught me loads and we worked together on many jobs (and still do from time to time). There was so much to learn (which I had assumed before the course.)
A training course is like the driving test. It's only after passing that you learn to drive. This is exactly the same with plumbing. They teach you to turn off the stop tap. They don't teach you how to turn the tap off that you can't reach properly and that doesn't turn. The old adage of "You can't get a job without experience and you can't get experience without a job" applies very much to the plumbing world. An employer has choice these days and will always choose the experienced person and won't worry about qualifications too much. (Ditto for a builder, electrician, etc.)
The training is excellent at RF - finding a job/being successful afterwards is much more difficult. The £8k is only the training. A van will cost, as will tools and some stock, public liability insurance and so on. You'll be looking at around £12-£15k in your first year and that's a huge amount of taps to fix (which will be most of your first jobs).
Not trying to put you off - just some meat on the bones of what others have said earlier - and a dose of reality.
Whatever you choose, best of luck!!