The white lines across the width of the lanes where they meet the junction indicate that oncoming traffic has to give way to traffic on the roundabout - the fact that the lane on the roght doesnt have one shows that no traffic should be approaching the roundabout through there. The writing on the other end of the road is also oriented so that cars coming in the correct direction can read it.

In practice, as far as I know pretty much every road in the UK is two-way unless signage explicitly states otherwise. So you don’t really think about this as you’re driving.