What is the safest way to turn around in a densely built-up area with a lot of traffic?

The safest way to turn around in a densely built-up area with a lot of traffic is by driving around the block. It minimises the risk of you surprising or being surprised by other road users.

You may only turn around or reverse if it can be done without endangering or obstructing other road users. If you are driving in a densely built-up area with a lot of traffic, you are likely to pose a danger or obstacle to other road users if you reverse around a corner or make a U-turn (which is often prohibited by road markings or road signs).