Dumb Aussie needs advice

Hi! My wife and I intend to buy a car and caravan for six months to tour the UK. We arrive early April and leave for Australia in early October. We travel for six months of the year across Australia in our 4.2 litre 4WD and 18 foot caravan  . . . . and love it! However, we're completely new to caravanning in the UK with its different regulations and towing capacity of cars, and so on. I was thinking of buying a 2.5 litre Subaru, simply because I can service it and strip it down on the side of the road if it breaks down ( . . am thinking Outback, but not sure if they do that in UK) 

Where can I go to get all the relevant details of hitching up a caravan to a car in Britain without running the wrong side of the Transport Dep't.

Thanks, in anticipation.

Bob & Virginia North