I've had problems posting recently. This is my third attempt to reply to this question. The others just disappeared without trace. Maybe my posts were too long so I'll try shorter ones.
Given your circumstances and stated aims, there is no need to become tied into a school or to get caught up in the world of competitions.
Most large schools should have a senior teacher who is qualified and capable of preparing you for professional exams. If you cannot find one the dance associations will be able to help.
The relationship with this teacher need be nothing more than a financial business arrangement, though hopefully they will talk through your hopes and aspirations and discuss your options.
The associate level exams are based around bronze level figures but you must be able to dance and demonstrate them, as man or lady, to a reasonable standard. You will need a series of private lessons to work on this and to study the theory as laid down in the relevant association technique book. Note, the IDTA uses a different book from that used by the ISTD, NATD or other more local UK associations, so make sure you study the correct one. Lots of homework and private study will save you time and expensive lessons. Later it will be handy to have a partner of friend to help test your knowledge of the book.