There appears to be a DNS issue which will likely take a few more hours to fully resolve (would the techies please excuse the pun) this is causing a kind of 'rolling outage'.
You can still access the site by removing www from the front of the URL
eg
http://ukmonster.co.uk/monster/ works but
http://www.ukmonster.co.uk/monster/ doesn't.
This should have happened overnight without anyone other than insomniacs really noticing.
My apologies of you've been affected by this.
Before I get inundated with clever responses about putting this info on the troubled site, I'm sure word of mouth, (anti)social networking and sporadic access will help spread the good news.
<insert smiley of your choice here>