Well, I must say this is a very ambitious undertaking and I wish the UK all the best.
The ESA is renowned for having top technical people and the fact that its experts could identify no immediate showstoppers is highly encouraging. That's not to say everything is plain sailing from here. The unexpected can always emerge to thwart best intentions, and in the case of Skylon the next hurdles may not be technical; they could just as easily be economic and political.