Darlick is correct.
I think the idea of the distance phase is for you to read and understand the principles. I don’t think the vast majority of people can remember much of what they learnt before they go on the brush up. When you go on the brush up it all comes flooding back very quickly. I had a lot on with my full time job during the Mod 2 distance phase so I simply read it through, took the progress tests (Which I nearly always failed) and moved on to the next subject. I understood everything I had read but I couldn’t remember more than 25% of it. Once on the brush up, away from home and work with nothing to do every evening except study you can soon get all of the facts and figures in your head.
My only advice with both the brush up and the exams is lodge away. Even if your Mum and Dad own the house next door to the training school, and your Auntie lives at Gatwick, don't tell them you're in town and check into a B&B. Secondly, don’t go home on the weekend in the middle of the brush up. Have a lie in on the Saturday morning, do a bit of study, go out for a couple of hours perhaps and then get straight back into it. It's a hard 3 weeks but worth it when the results drop on your mat.
Good Luck
SW