Just to put a different spin on this (and no I have nothing to do with G4S)
How's your network?
After you finish the course, have you got 'an in' to get you working?
If you have a read of this site you'll find loads of posts about how hard it is to find work, or to find consistent work beyond a couple of jobs a year.
Regardless of how good a course is (and lets be honest, they all fall well short of the mark of the course you get in the Police or RMP as nobody will ever pay out for it) in the end you get the same 'qualification' and licence.
Then you're largely on your own.
If you pick a crap TP with a crap reputation then you've no chance, but picking one with a good rep won't open as many doors as picking a course that has good connections to live contracts, where the best people get an interview and genuine opportunity of work.
I know people who've done what I consider to be some of the best courses around, they're not working CP
I know people who've done an average course like Phoenix and are getting work, simply because they showed the right stuff to the directing team, completed a course that the contract holder recognises as delivering what they need and gives preferential treatment to.
Food for thought (and while you're working and getting experience, you do CPD to fill the gaps left from the average course)