Never done Films, done some TV, Radio and on the News (not in that way) including BBC 1 and ITV, mainly because some friends where in the game plus I used to do a fair bit of Engineering Coms work on Outside Broadcasts and Contracted Shows.
I appeared on a few live show with Uri Geller once or twice on Grampian and STV, that was a scream, the guy was a joke, also appeared on National Motor Show at the NEC, mainly because you rub shoulders with the right (or wrong) people and there Researchers can't be arsed to go out and find real people, so you end up doing a stand in, pretending your someone your not.
Ive had some close friends nearly crashed there car, listing to some of the garbage I had to come out with on BBC Radio.
As Tunnie says most of it is unpaid, but claimed expenses can be good, together with free Hotels and Bars for a few nights.
Are you a member of Equity?, fairly sure any talking roles require that, otherwise you just end up doing roles as a 'Mumble'er' in the background.