Got wot appears to be a rear offside wheel bearing that has collapsed.

No prior noises or problems.

Taken the wheel off and removed the brake caliper. Just turning the hub by hand gives an awful clonking and screaching noise.

Is the bearing replaceable on the mk11 or is a complete new hub unit required? Also wot special tools am i likely to require and is it possible to do it without a press to remove/ refit bearings?

rear wheel bearing is a complete assembly with a hub flange it's a slide off slide on bearing no pressing required, rears are very easy

http://www.njnoordhoek.com/?p=905 this is a helpful guide

Thanks for that, much appreciated. I'll get one ordered

I'm about to do one on my mk5 golf. Watched a couple of vids on YouTube and seems easy enough - I'll quite enjoy getting the spanners out for a change. 

Replaced one on mine on the weekend. The bolt is a M18 spline and was extremely tight, took a while to get it to crack. But once that was done nice and quick.