On track, the first thing you notice is the circuit is pretty bumpy. Secondly, it is very, very fast. The climb from the start line up Avon Rise is effectively a straight with a kink in it, but do watch out for standing water if it has been raining.
The first corner, Quarry, is one of the most tricky in the UK. It is tighter than 90 degrees, but what makes the right hander complicated is the kink to the left before the entry. This kink is on a blind brow, so you will need a couple of slow reconnaissance laps to work it out. How you take this kink is dependent on the stability of your car under braking, as it is likely you will be braking over this brow.
In a front wheel drive car, I tend to take the left kink to give a late, late turn point with late apex for the right hander. I feel that this negates any understeer and give a quicker exit. However, it does leave you vulnerable to be passed. Some cars find it easier to take a straight line over the brow to the natural apex. This gives the benefit of a straight line braking, but the earlier apex could cost you speed on exit. This was probably more important before 1998, when the section that followed was absolutely flat out, including the scary Old Paddock kink. However, there is less of a premium these days on exit speed, as Quarry is soon followed by a chicane, called the Esses.
This should provide an object lesson to chicane designers. Far from being the usual stop start affair that castrates a great circuit, the Esses are wide (two abreast is possible), quick (3rd gear in most cars) and challenging (get it wrong and your exit speed is compromised). Try and look through the Esses to find the second left apex, this will dictate your first apex.
As a result of the Esses, Old Paddock is now easily flat in almost all cars, though can still spring a surprise in the wet. Get this part right and you will be well placed to overtake into Tower.
This is my favourite overtaking place at Combe (I passed 4 cars in consecutive laps here on my way to a win once), simply because you can afford to compromise your line into the corner, as the exit straight is so short. Elsewhere at Combe, a great pass is usually followed by your opponent slipstreaming past on the following straight. Tower feels claustrophobic due to the lack of run off, but is a rewarding bend. A little bumpy but with a late apex you miss the bumps and can get the front of the car nicely planted for the climb that follows.
Bobbies is tighter than the Esses and is probably second gear in most cars. Try and straight line as much as possible, but although the exit is wider than the entry try and avoid using the 'grasscrete' on the exit. It compromises traction, and Mr Strawford will not thank you for making his circuit look untidy.
A clean line through Bobbies sets you up nicely for a pass into Camp Corner. One of the few corners in the UK that is in full view of the pit lane, you really don't want to mess this one up in front of your mates and mechanics! A wide, long corner, the apex is initially difficult to judge. It is about two-thirds of the way around the corner, just when you begin to see a clear line through the corner to the pit wall. It is vital to carry as much speed through here as possible, as it is followed by that long climb up the hill to Quarry once more.