10 days for driving round the whole of England? - whilst its pretty small by US standards, you need to be aware of the density of the traffic and average speeds, otherwise you will spend most of the time in the car and wont see much. Unless you want to stick to Motorways (boring), the A Roads can get clogged, I'm in the south west and you are lucky to average 40mph due to trucks, caravans, tractors, old biddies in Nissan Micras etc.
I am just saying just dont be too ambitious.
July/August is school holidays here so make sure you book accomodation in good time. A fall back would be the souless Travel Lodges which are about £50 per room per night (no food)
Depends what you are looking for, scenery, culture, old stuff etc. I wouldnt go further north than Birmingham in that time (but dont go to Birmingham)
Scenery - Cotswolds, Cheddar Gorge, Brecon Beacons, North Devon Coast, South Devon/Dorset Coast
Old Stuff - Bath, Wells Cathedral, Warwick Castle, Windsor Castle, Stone Henge, Portsmouth Dockyard (Victory/Mary Rose)
Military - Bovington Tank Museum, Dorset,
aircraft museumsObvioulsy if you are venturing in to London there is loads of stuff to do
Anyway, have a great time, hope it doesnt rain like it did last summer
