You do not have a menu item pointing to the list all Akeeba Ticket System categories for the English (United Kingdom) language. Ticket links may be broken until you add such a menu item.
#1015 – JoomSEF Error
a quick glance at the source of the homepage revealed errors in the twitter image (right column, near the top of the page), and most of the social icons in the footer: they are all encoded with base64 but without "" surrounding the data. I suggest you use a sprite since - besides the error - they make your page unnecessarily heavy and must be re-downloaded at every visit, it's just useless to compress images inline with the markup; it's even debatable including base64 in the css, but in the html it's downright wrong unless the images change on each visit - but social media icons hardly ever change!
Besides this you have a K2-related jQuery error (calling noConflict() before the jQuery is available).
Our main activity is making sites faster, but from a quick glance I would strongly suggest you rethink and organize the code, and document the features, because as it is it would be a massive job, involving at the very least removing half a dozen extensions, 20-30 libraries, and create a single one to perform all the work.
That said, we do not produce JoomSEF, and are in no way related to Artio (althogh I know the product of course). If you were referring to another of our extensions, I didn't see it in use on the website and cannot guess if it were toomanyfiles maybe? but you can't use it with such a messy markup, I am guessing it would never be able to work, you need to fix the code first! Or if it was LittleHelper, maybe the issue was simply in the .htaccess files, but with that much content I would optimize those as well.
If your site is already live, I suggest you work on an offline version as these activities may temporarily introduce errors. The matters I outlined are fairly serious and you should look after them quickly.