M4 is the main route west from London to Bath and southern Gloucestershire; expect about a two-hour drive. From Exit 18, take A46 south to Bath. From Exit 20, take M5 north to Gloucester (25 mi), Cheltenham, and Tewkesbury; from Exit 15, take A419 to A429 north to the Cotswolds. From London, you can also take M40 and A40 to the Cotswolds.
Parking in Bath is restricted within the city, and any car illegally parked is likely to be ticketed. Fees for towed cars can be hundreds of pounds. Public parking lots in the historic area fill up early, but the Park and Ride lots on the outskirts provide shuttle service into the center. In Cheltenham and Gloucester, garage your car or leave it at your hotel and forgo the stress of finding parking and negotiating one-way streets.