Dr Tre
This was done to death recently so you might want to use the search function to review the earlier thread.
Anyway I think it is fair to say the concensus (and certianly my view) was that you are completely wasting your time filing. For a VFR FP, or even an IFR FP outside CAS, it is doubtful whether the plan is promulgated to en route class D providers, and even if the FP is specifically referenced so that it is, the providers are not in the least bit interested in giving you any priority in consequence.
Any class D controller will consider his commercial traffic load at the time you ask for a transit and the professionalism of your request. If he can fit you in with his CAT and you sound like you arent a trouble maker you will get the transit.
That is true at any rate of most class D. There are some areas of class D where you probably should assume you will not get the transit - which include for example London Stansted, Gatwick, Heathrow (class A SVFR), and Manchester.
(you dont say from where to where, but if you do, I suspect more than a few of us on here have been that way before and can give you the heads up on the best route and what you might expect.)