First off your really need someone like Steve Jenks to do a site assessment so that you can find out what can be built as to size/level of track for the funding you
will have from the council, you don't want them building it for you, you deffo need someone with experience to build it right first time.
As for infrastucture well BC should be able to tell you that, if not get intouch with Bristol or Burnhams bmx club for advice. Myself and a few others have just got
Hereford bmx club back up and running and waiting for funding to rebuild the track but as Zippy says you need someone with bmx knowledge and like your BC guy
said theres nothing around your area.
But first find out what money you have to pay with, a good track regional standard will not be cheap around £50,000 or more