That's not bad.
Unfortunately it would cost me and the family £80 return for the fare
to Stansted (4 hour-ish journey) plus the trouble of crossing London.

Should've used a car...

To stansted? And risk getting trapped on the M11 in massive 4" snow
drifts?

M11? Why use that? From Hampshire, go up the M3/M25, round to J21A, up the
A405/A414 (or off at J22 and through Colney Heath, and out onto the A414,
cutting off all the roundabouts but one), then A1(M) for one junction, and
then A414/A10/A120. Cuts off that PITA section on the M25 past the lane
drop at the A10 junction. Don't know if it'd be much quicker on a clear
run, but I doubt there'd be much in it. There are a few roadworks on the
A10 around that section at the moment though.

FWIW I never use the M11 going to Norwich from anywhere West of the M25 - I
always head up to the A1(M) as above, and then up through Baldock, and along
the A505. Much nicer drive, and very little in it, even assuming clear
traffic on the M25/M11.

Peter