Classicwings,
Apologies for the delay in responding to your question, been a bit mad here the last few days!!
I was already a qualified controller when I first attended the college in Cwmbran, so I'm afraid I can't answer your questions from any experience of my own. I do, however, know one or two people who have done the Aptitude test and have found it very useful, although it was employer-sponsored!
Regarding finding work placement for post-course OJT, don't expect the college staff to do the running around for you. Internet facilities are provided in the Students' Common Room (although connectivity can be a bit hit-and-miss; and there's always a queue for the use of any of the 3 PCs at peak times, i.e. during scheduled breaks) as well as industry journals and magazines. Don't forget, you're likely to be on the course with students from all over the country, so there'll always be someone with a bit of insider info/gossip that could be worth following up on. Also, as invariably happens, if anyone hears about any possibility of positions becoming available, that info usually finds it's way to those who are in the market.
Basically though, the onus is on you to help yourself where finding a position is concerned. So get your list of SATCOs/MATs out and starting firing off those CVs and letters of application. You will get some assistance from the staff and other students, but don't forget that they have other responsibilities.
I'll put it this way: of the two courses that were running last time I was there (probably somewhere in the region of 24 or so students, of whom a large number were self-sponsoring, and not just ex-mil types) I think only two individuals finished the course(s) without a firm offer of employment and completion of training. I'm almost positive that has now been reduced to one, and it's not that long since I was there.
You'll only get out of it though what you're willing to put in.
Good luck
P.S. If you have a Wi-Fi enabled laptop, bring it with you. The college will provide you with the password for their public network so that you can access the internet to hunt for those jobs from the classroom or the common room, without having to try and beat the rush for the PCs! Connection speeds are perfectly sufficient for general browsing and emailing, but don't try to hog the bandwidth by trying to download large files or watch any streaming media! Wouldn't be very fair on the other network users, and I'm not sure the system could handle it!