new tow licence CONFUSED!!!

Hi, can someone help. I currently have a cat B only on my licence. My car kerb weight is 1350kg's and caravan is no way over 1300kg's as my 85% kerb weight for my caravan is only 1150kg's........... Okay here's the crunch! After reading the DSA website, my understanding is that as long as my combined weight is less than 3500kg's then I can tow on cat B licence. On this caravan club webite it is suggested the same. However when I phoned my nearest site for some towing lessons, (being a sensible new comer) I was informed that actually I would need to do the test as my van will weigh more than 750kg's regardless of my overall tow weight being less than 3500kg's. PLEASE SOMEONE PUT ME OUT OF MY MISSERY! obviously I do not want to pour good earned money down the drain, Chris