finally had another go at this... took a while to get around to as i had some muppet at the VW dealership order me the wrong bolts when they had the right ones in stock all the time anyway, even tho i brought one of the bolts in to show him! anyway....
I drilled out the retaining screw on the right disc, so that side is all done and sorted, but tomorrow i'll have another go at that caliper bolt. spent a bit of time on it today, cut away the rubber, and your right, grips wont budge it.
My idea of using a grider to file it down might be a bit extreme, there's not much room under there and i'm likely to hit the brake line!
bomp's plan might work, but i dont have a hacksaw... or a screw driver bit wide enough.... mr blues way of wacking a socket over it might work, tried a ring spanner earlier, but didnt have a hammer either (i know, i seem to have a complete lack of tools just lately).
so the plan is to get a hammer, whack the spanner over it give it a good yank and then curse and swear when it slips and i cut up all my knuckles, i'll then go buy a hacksaw and driver bit and have a go at bomps plan...
wish me luck