HELP Severe cramp in calves

Hi hope someone can advise me of any exercise / diet to reduce the onset of
cramps in my calves after a ride and ocasionally durring a time trial run
the cramps are very severe leaving me compleatly debilitated with the pain
for about a minute and tender calves for about a day.
Im not a cycling pro , got back into road riding about 6 months ago and have
beeen gradually trying to improve my fitness on a local TT route here in
northamptonshire ,UK.
I REALLY enjoy my cycling and want to find a solution to this. Any
sujestions would be greatly appreaciated.

Rob D