I would really recommend that you DO NOT drive in London. Do not even think about driving in London. Not only is the traffic a nightmare, it's all but impossible to get around, even with a satnav, as many junctions are impossible unless you know exactly what you're doing. The Underground is very good, and there are stations just about everywhere, especially in the centre of the city, so you shouldn't need to drive anywhere.
There is so much to do in London I wouldn't know where to start advising you. See the sights, visit the museums and galleries, however long you're staying for it won't be enough to see a fraction of it.
Hotels are really expensive, mind. If you're on a budget, consider a "pod" type hotel - there's a few of them springing up around the city. Budget hotels tend to be further out, and quite some distance from the city centre.
As for the concert - Hammersmith Apollo is a nice theatre, but it's on a main road, and there's no car parking or anything at the venue itself. The underground station is across the street, so it's easy to get to. See you there!