Good luck to you, but with just an unvalidated ADI rating you are more or less unemployable - Ive just checked and I have CVs from 15 ADI only ATCOs with previous validations at other, often major airports, who have written to us for jobs to be trained onwards.
We get an average of 4 additional CVs a month from people in your situation seeking posts.
My advice to you is beg, steal or borrow to do the APS course directly after the ADI, preferably the APP as well.
Times have changed significantly in the last 10 months, airports are training their own staff for ATCO courses, they are recruiting, (wherever possible) for ATSA posts intrenally and the thing you must pay particular heed to is that, despite whatever has been posted here, unless under exeptional circmstances, they are not taking on people with anything less than either ADI and APP and/or APS ratings - nothing less will do otherwise you'll be in limbo for many years to come.
It's a huge commitment on your behalf but, if you consider that you are capable, go for ADI/APS and APP if possible, either of the colleges will bend over backwards to assist you to finance all three ratings, after which you'll almost certainly get a job straight away and be in a very strong position to negotiate the repayment of a large part of course costs.
Youve got a huge amount of work and commitment ahead, the very best of luck to you, go for it - but only all 2 or 3 ratings, not just ADI otherwise you'll be wasting your time and a fantastic opportunity.