Upon investigation on the Mk2 wobble problem I have once again cured it - I think (all be it for the short term - for now).
Thanks to TigerFish & Osteo. Taking off the caliper (the pistons are pretty much fully retracted due to the new pads), I supported the caliper and pressed the brake pedal four or five times. Only one piston came out. I retracted that and then used the retractors to block the one that came out and pressed the break pedal again. This time the other one came out quite a distance.
Trouble was it proved very difficult to push back in. I eventually did this, using the retractors and my 2 tonne jack handle for leverage, and repeated the procedure 4 times. Eventually the sticky piston was easy to retract by hand (using the retractors - without leverage).
I also noticed that the new disc was warped!!! With the wheels off, I tightened all the wheel nuts to hold the disc in place and spun the wheel, there was a fair bit of movement to the disc! Looks like another new set of discs for me then.
The wheel wobble has now gone, but I think will replace the discs, yet again, this time with Mintex. I will also get the calipers re-furbed at some point in the future.
Cheers guys,
Phil