I used to have a mobile broadband dongle. Now I have a smartphone which has a data allowance and a "tethering" ability. What this essentially means is that my phone becomes the "dongle" on those rare occasions when I need mobile Internet access on devices other than the phone. You might consider this rather than a dongle.
Either way, you'll need a provider that has fast access speeds and a high data allowance. Pretty much the only one that offers this is 3:
http://www.three.co.u...port/Mobile_Broadband
However, 3's data coverage is not great. Check the 3 data connection at the caravan club before committing. Ideally, find some other resident who has got it working. If all else fails, try this checker with the postcode of the caravan club:
http://www.three.co.u...opup/Coverage_checker
But I'd hate to base a purchase decision on that checker alone ...
One other option you might consider is TEP:
http://www.tepwireless.com/
I've used this when I visited Spain for a few weeks and found it to be a great service, much cheaper than using my own data connection. The service was originally for American visitors to the UK so I would imagine you can get a TEP device for use here too. If you only went to the caravan club infrequently, and otherwise did not need mobile internet in the UK, this could be a good option for you ...