Well, a bit of an update here!! Unfortunately the resolution is not going so well
Managed to finally get a courtesy car yesterday after several letters to dealership, and VWCS. Engine has been stripped down 'timing chain has slipped but the tensioner is not responsible' I do not care what has failed - my GTi should not have engine failure at this point in its life (4.5 years, 47,000 miles). I have been told no 'factory goodwill' spoken with VWCS who said they will sort something out - 1 week later the deal on the table is No contribution from VW, dealership will subsidise the repair to a final cost to me £3500. I was furious (but did not go ballistic - I want these guys to help me) told them that was not acceptable car sold to me was not fit for purpose etc etc. Waiting for further call.
Not sure how to play things - anyone have any experience of the law or should I walk away £3500 worse off and learn a very valuable lesson re: VAG group. Its all a bit disappointing given some people's outcomes with VWCS.
Thanks for the advice and I would urge other 09/59/10 GTi owners to think hard about their future!!