geographical filter page - of venues/dances in the Mid West of England (+ De Ddwyrain Cymru).

OK the page is fairly stable and ready for a bit of comment.

what it sets out to do is inspect 4 of my pages and generate a subset of the data based on geographical proximity.

The epi-centre/focus can be chosen by town/village from a list which is culled from the same pages.

Those pages can be displayed individually.

The distance info can be replace with post code or grid references (2 styles).

I may extend the scope (eg Radio Stations) and chronological info is penciled in but I am having difficulty with alternate weeks and finding a reliable datum for each one (was it ever thus?).

So - is it fairly easy to understand?
are there any browsers that make it go wrong (eg Opera 10.5x)
have I wasted a month of my life trying to script it?
do bears poop........................