What should Father of the bride wear?

I think it's entirely up to you. We're going with black tie but my fiance is going to have something slightly different to the groomsmen so he stands out. I think so long as your fiance is happy with your dad being in uniform then that would work but just also make sure your groom is clearly the groom so maybe something to elevate his outfit compared to best man etc.

Totally up to you - as long as you and your dad are happy with it, he can wear what he wants.

I actually prefer it when the fathers of the bride/groom wear their own thing as it's a nice way of letting them stand out from the groomsmen/ushers, because after the bride and groom, the parents are surely the people most affected by the day, so they should stand out a bit.