That's fairly high mileage you are putting in in these temp's and at this time of the year, what sort of average are you doing? I know that area fairly well, in the summer we cycled from Oakham to Sheringham and back on a Sat and Sun, always windy in the Wisbech area.
I'm averaging about 100 a week i suppose, mainly from 30 miler "training" rides round the fens.
I'm lucky to have "extra padding" by being overweight, meaning i can keep riding without too much cold discomfort.
As for the wind ... i've cycled in many parts of the uk and find the wind locally the most annoying!
Once you get just over the A10 into slightly hilly norfolk it dissipates quite a lot.
I haven't been over near oakham, the closest being morbourne/haddon last weekend. (West of peterborough).
I've cycled around sheringham, in fact if you'd like to try a scenic ride i can recommend the coast path from wells to sheringham.
Not many people can cycle up the last bit to the lookout tower west of sheringham due to its steepness! (On a mtb obviously).
The view from the lookout station, back towards wells: