I went to WIM on tuesday for a geometry set up, its well worth it. It would be well worth the 4 hours, i live in the midlands & had the same 4 hour round trip.
The difference is unbelievable, i would highlt recommend it.
With WIM you can stay with your car & watch whats being done & have it explained, you dont get this with ATS.
It cost me £100 for the geometry set up & it took about 1 hour.
Hope this helps