In reply to Piers:
There are no worthwhile crags of any sort (suitable for beginners or otherwise) within 1 hour's drive from Milton Keynes.
Markfield is the only place I can think of that even vaguely fits the bill, but it's:
a) Awful
b) Probably a bit banned I think
c) A terrible place to take beginners as it's awful
d) Awful
e) Falling apart and devoid of gear
f) Awful
Sorry to be the bearer of bad news, but you really would need to drive to somewhere like Harborough or Birchen for what you're after.