Possibility of changing Philosophy with Political Economy to Economics

Hey all,

The title pretty much sums it up so yeah:

Does anyone know how easy it would be to change Philosophy with Political Economy to straight up economics.
Both have predicted AAB although economics is (AAA-AAB) and I meet that requirement with my predicted's and hope to in the summer.
I spoke to a lady about switching but she said I would have to take my first year anyway, but I believe that was if I already turend up without changing.

I have already applied and put it as my insurance.

Thanks for your help