I know of no park and ride that has been effective without a compelling/ alternative reason to use. For example Oxford where it is virtually compulsive, or Stratford, where until the Parkway railway station was located adjacent to th park and ride, it was hardly used.
Visitors will always want to park close to the town centre and will attempt to do this first, then find a space nearest to the town before using the park and ride as a last resort. All we will be left with is a black one opted area, little used, causing water run off and drainage problems, causing light pollution, and taking away more valuable green space from this beautiful part of Leamington.