Everything in consulting is high risk. If the firm doesn't find you up to scratch, they'll happily dump you in one of the appraisal rounds. So the risk works both ways.
A piece of advise on the MBA - in the eyes of the consulting firms, atleast the big ones, all MBA programmes are definitely not equal and I don't honestly think that B'ham or Durham are amongst their most wanted list (no matter what the ratings are). I'm sure you'll find a job at the end but don't assume it will be a top firm, unless the market really takes off in the next few months and there is a hiring frenzy.
You have a PhD from UCL, a post-doc from Stanford and now soon an MBA so you are going to be a very well qualified candidate, but with little experience of the real world. You will probably get entry level (or just above entry level) consulting offers which you should most certainly consider because it will break you in easy as well as allow you to learn the ropes as you go along.
I got in as a PhD with many years experience, mostly in academic research, with little business experience and at a mid level consulting track and man did I suffer because of the dramatic shift in just about everything - workstyle, lifestyle, etc etc. So take time to learn and I am sure you will be fine.