When a roundabout's first exit is straight ahead, do you have to signal left?

I've just moved to a new town and not encountered roundabouts like this before. I'm pretty sure you do have to but my mum disagreed. I'm a very experienced learner so I don't really want to have to pay an instructor for an hour just to find out about signalling at roundabouts. These are actual roundabouts I am talking about, not mini roundabouts. However, I'd be interested if the rules are the same or different for mini roundabouts, as my instinct is that at a mini roundabout even if it's the first exit, if it's straight ahead you don't have to signal. If there are any driving instructors/testers out there I'd love to hear from you! Anyone else's help also appreciated!