There are charts on the web and diagrams in the manuals but I've always driven the car out to a piece of quiet and dark road and adjusted them there. Road needs to be very flat and without any camber if possible. If you adjust the main beams to hit the road about 75 yards ahead you should be fine. A little bias to the gutter is not a bad idea but it only needs a few degrees.
Depending on what lights you have fitted the main and dip beams are usually about the same brightness. If one of the dips is dim it's probably just a corroded contact somewhere. Check the multi blocks and earths to the inner wing.
Good luck with the MOT.