The Times (London) Dec 25, 2016 has an article of the best wintertime walks in various parts of Britain. 28 walks are described, with distances varying from 1 to 8 miles (most in the 5-mile range). Locations range from Cornwall to North Yorkshire, Wales, and Scotland, but most are in the southern half of England.
See http://www.thetimes.co.uk/edition/magazine/boxing-day-walks-mmfpv75hh
The reader comments are worth a read too.
(Note The Times requires registration to access a limited number of articles for free.)