A bit late in replying, but the Museum is just off the Market Square, and very close to where the Canal boat trips leave. From the coach park, you will walk past the place if heading to town. Long Wharf side style building, although the Wharf was filled in a long time ago.

Parking is reasonably good in Newbury but if you are coming to spend a day then the parking can add up as most is chargeable. That said, Sainsbury's on the A339 has an hour free and the museum is a five minute walk. You can see it from the top deck so if you want a quick look there's your answer. There is a car park below the shopping centre in Parkway which is usually reasonably free but a pound an hour. The museum is a walk up Parkway with the park to your left and over the bridge. It is directly in front of you. Don't be tempted to drive over the bridge, it is buses and taxis only. Expect a fine from West Berks Council if you do. There is a wharf car park alongside both the library and the museum, Pound an hour though. This car park is usually busy and parking can be a problem.