I tweaked the website some more over the last few days based on feedback I received in the cats...
I re-wrote the form validation as some Mac Safari browsers didn't like the pop-up validators or the client-side stuff generally. So now it's pretty much all server side. I found an intresting defect in mootools/Kwicks relating to "domReady", which I fixed by switching to "onLoad"... that created a 404 which screwed up Macs in some circumstances.
The new certificate isn't recognized by the standard Firefox distribution.. I don't control that: click "accept" and it's all fine of course.
I re-wrote the pictures section as it wasn't looking brilliant. We now have prettycalendars from which you can select your day and view the pictures. That's live and running. I'll switch it to Ajax eventually as that should be easy enough.