Whereabouts in Kent are you? There's a massive massive shortage of storage in Kent and most places have lists for at least two years. We're on a brand new and as yet un-advertised site but it would help to know your rough location.
Oh, if anyone finds a decent one let me know. There was a big one in Gravesend but they sold it. We now have ours stored at in Horsham on a site we go to.... its a bit far though.
The caravan shop in Orpington has numbers for local farmers who store if that helps you out.,
Many places are not advertised, deliberately so that thiefs can't look through the yellow pages! So local caravan service places, dealers, farms, riding schools are all worth ringing up - if they don't do caravan storage they may know someone who does.