Chesham is situated about 25 miles (40 km) North-West of London. The cleanest route into town is down the A416 from the A41. The A416 can be very congested particularly when somebody has done something silly on the M25.
You can catch a bus from Berkhamsted, Slough, High Wycombe and Aylesbury.
The Metropolitan tube line has a branch terminating at Chesham.