That depends on the size of the measuring device you use. If you were to be sailing a boat near the perimeter, then your distance traveled would be much less than walking its shores due to the fractal nature of geo-mass.
I know that this is not a direct answer, but it may shed some light on the trouble of finding an answer. To further answer your question- how will you be traveling and how approximate can you afford an answer?
Okay, for starters, circumference is used only for circles and spheres. the UK is neither so therefore it has no circumference.
It is around 4,228 miles.
As the crow flies, its around 200 miles
Approximately 90 miles, or around an hour and forty minute drive.
Around 400 miles from the cost of Argentina but I can't tell you how far it is from the UK.
Uuuuuuuuuu...Un Chingamadral:)
About 310 miles
The UK is 94,526 square miles
213 miles
its probably about 200 miles from UK
76 miles
About 21.3 miles by road.