Email RVC and ask them for advice.
Ask them if the gateway course counts as a vet choice or not (remember you can only apply to 4 vet courses)
If it doesn't, and it would be your 5th choice, you should definitely go for it.
But if it doesn't, I personally wouldn't apply to both. It would be a waste of your choice.
Applying to a different uni instead would increase your chances of getting in.
You can also post this question in the VetMed section of TSR and see what others say.