Unless I've misunderstood their literature, ASTAC College (Rudloe Manor, but shortly moving to Gloucestershire) do actually run a 'cadet scheme' of sorts. You'd have to check the details with the college, but I suspect, that like airport sponsored training of ATCAs, it will only be available to their employees (Simulator blip drivers).
An ATCA / ATSA post is a good 'foot in the door' strategy and provides excellent experience for later applications, but subsequent ATCO training is by no means a certainty, so it's not necessarily a very quick or reliable way to obtain a licence.
HOWEVER - There is a growing shortage of ATCOs, not only in the UK, but throughout Europe, and sooner or later, the traditional methods of attracting qualified, experienced ATCOs from other units, will no longer be a reliable way of ensuring that staffing requirements are met. Before long I suspect, more units than at present will be looking at ways of implementing some sort of cadet scheme to address the shortfall.
In any event, a job within ATC, whether it be ATCA or blip driver, will pay the rent, enable you to reduce your debts and at the same time provide useful background knowledge while you investigate other opportunities.
Good Luck
RC