It's also unusual for a dojo in the UK not to be part of a BAB-registered organisation - if you look here
there is no mention of this dojo in Stoke.
and that proves what Alex? Is that a comprehensive list of all BAB affiliated clubs?
No is the correct answer.
Is membership of the BAB dependent on achievement of some technical qualification that clubs outside of the BAB do not have.
Again - the answer is No.
Its not that unusual, but it is irrelevant.
FWIW I'd say check out all the clubs and go to the one that best matches personal aims.