Update,
Garage showed me the mot spec and unbelievably these cracked tyres dont constitute a fail, needless to say they wouldn't replace them, they then proceeded to show me at least five other bikes, one of wich was the m.o.t. testers own machine with even worse cracks than mine. I have decided to pay for a new one (from a different dealer, sod em)but it does concern me, so if anyone out there is using Continental road attac tyres, please check your front tyres for cracking in the tread grooves, i would be interested in any feedback as mine is obviously not isolated and i will be contacting Continental.
Thanks