You Do Need power plug adapter while traveling from Tanzania to United Kingdom (UK).

Here is Why You Need An Adapter

The outlet and plug type used in United Kingdom (UK) is G and in Tanzania are D and G. This is how they look like.

Tanzania

In Tanzania, outlets of type D and G are in use.

Type D

Type G

United Kingdom (UK)

In United Kingdom (UK), outlets of type G are in use.

Type G