I live in Serbia and have 2 passports, a Serbian and a Croatian. My Croatian passport allows me to travel freely in Europe (for the time being! ;-) )

I'm flying to the US and have got a VISA under my Serbian passport. I'm flying back from the US via London. If I use my Serbian passport at passport control in London, I won't be let in as I need a VISA to the UK which I don't have! uh oh!

However, if I show my Croatian passport at passport control (where I don't need a VISA to the UK as it's my Croatian passport, you get where I'm going with this? ;-) ) will that be ok?

I'm worried that when they scan my Croatian passport, it won't sync with a ticket or a departure terminal), can anyone offer advice on this?

Any advice would be greatly appreciated.