a) Christian Wolmar saying that this road budget is a rehash of an announcement last year, with actually less money in real terms, and won't include much actual new road building http://www.ibtimes.co.uk/autumn-statement-2014-road-ruin-david-camerons-15bn-road-building-programme-1477733
b) any environmental concerns
I don't really see how anyone can think that road building in the South East (e.g., the part of the UK corresponding broadly with the old Network South-East area) will actually work. By and large everything is at capacity and expanding things will just move the bottlenecks elsewhere, and it is not as though you will be able to get into the towns and cities when you get there. And where there are major bottlenecks that might usefully be alleviated, the reason they weren't before is that they were really unpopular (that is to say unpopular amongst the 'right people' i.e. not just the greens / hippies). See in particular the suggestions for somehow bypassing the A34 past Oxford.