I've noticed in the game vids that there seems to be different character accents used when your are shouting out warnings and alerts and so on to your other team mates. are these locked into the game by character default (soldier, engineer, medic, operative) or can you select what accent your character will have in the customisation screen?

You can change your accent, yes. You pick it when you create your character, then can never change it ever again.

so do you know what the different accents will be that you can choose from?

This. If you don't the accent of one of your character, you can always delete a character and remake them from scratch.

It was in a video at one point. How many accents. I think it was one of the videos that got pulled. So, off of memory, you can choose six or seven, and each shows the actors name next to it.

There are 10-12 accents, I don't remember.

8 voice packs to choose from according to Wedgwood and co. on several occasions.

they should have already have thought about different Accent for players if they havent thought of that then WOW.

It seems like the Russian one was scrapped? And I have yet to hear this Asian one :l

Anyways:

There are 8 packs to choose from, when you create your character this is one of the first things you gotta choose, when you hold on one of the voices you will hear an example line so you know what you will get - You can do this over and over again since the lines always change and are random

There's about 10-12 accents in the game. They're not locked (why would they be, they're accents?)

There's a few American-sounding accents, and the rest are British (English, Scottish, Irish) and some African ones.