The pool our group normally swims at is under renovations until November...!! We're now at a diff pool but it's all ok!
Is there a university near you & could you use the pool for a while??? I too wouldn't do the pay as you go idea.
Best of luck with the open water swimming time!
The other thought is & i'm not an IM person...can you do simulated dry land exercises for your swimming? I haven't a clue if that would get you up to speed...i'm babbling..sorry..