If your pastor okays what you are doing and you get the proper dispensation and also have your marriage validated in the Church if necessary (I think it’s necessary but I have not checked into this recently)
No, a validation is not necessary in this case.
For a Catholic who wishes to marry, it is necessary to follow the ‘form’ of Catholic matrimony (ceremony in a Catholic church, presided by a priest or deacon). What the OP will do is get this requirement dispensed. (Technically speaking, it’s the bishop who can dispense the requirement, but he delegates this to a person in the diocesan canon law office.)
Once the requirements of form have been dispensed, it’s a valid wedding, even though it might take place in a Protestant church (or JP’s office!), and without a Catholic minister present. There will be no need to convalidate the wedding with a Catholic ceremony afterward, since the Church views the wedding as already valid.
As others have mentioned, the OP would need to work with his pastor, and follow the usual requirements for marriage prep (paperwork, Pre-Cana classes, meeting(s) with the pastor, etc).
Since this requires additional processes (i.e., the canon law office’s involvement), it’s wise to get to your pastor ASAP, in order to get the ball rolling.
One last thought: back in the day, when a Catholic and a non-Catholic Christian wanted to marry, they were
both required to sign a document saying that any children of the marriage would be baptized & raised Catholic. That’s changed. Now, the Catholic party signs the document attesting that s/he knows that it can be difficult to continue to practice the faith in a mixed marriage, but that s/he intends to do exactly that; in addition, s/he promises to do everything in his/her power to ensure that any children from the marriage are baptized and raised in the Catholic faith. The non-Catholic party does not make any promises, but merely witnesses the promises that their Catholic fiance/e makes.
Hope this helps!
Congratulations and good luck, @DM_P!