It does sound a good idea. Isn't the CWL based FCA actually a Skyservice A/C with a SkyService Flight deck? That would mean that there wouldn't be an extra a/c to move anywhere, just the Thomson 757 to CWL and the current FCA a/c will stay.
The FCA - TOM merger hasn't been given the go ahead yet though so it maybe TOM to CWL and FCA stay the same.