I'll answer part 2 first:
No I haven't got every UK club listed. Some don't have a website (or I haven't found it / it's not been submitted yet).
Now for part 1:
OK I can see how difficult to count they can be. I've taken time to count them today (02 March 2009) but the number will change as I discover more or some go off-line.
There are 13 National clubs and 252 local clubs listed as of the date above.