I would recommend joining one of the major clubs, Caravan Club or Caravan and Camping Club or at least looking at their respective websites before you take the plunge, also of course there is this website.
There is a wealth of information out there, for instance in the CC handbook there is all the towing info and advice you are ever likely to need, it's probably on the website too in the non members area.
Your car at 1400kgs sounds like an average saloon so as a newby you shouldn't be considering any van that goes over 1190kgs fully loaded - dont be confused by towing limits and if as you say your towing limit is more than the cars kerbweight don't be tempted to go there! Look up snaking in search if you want to know why or look at accident statistics for caravan incidents involving outfits overturning on motorway downhill stretches.
Don't want to scare you - it's a great hobby but you gotta be safe!