Informal Forum Guidelines - Convert coal shed and outside toilet?

Hi

I was wondering if anyone would be able to give me some advice.

I have a 2 bed terraced property to sell - currently the only bathroom is upstairs accessed by walking through the rear bedroom.

Downstairs at the rear of the kitchen - I have an attached outhouse, outside toilet and coal shed.

If I was to convert the out houses into a downstairs shower room, would I need planning permission?

I am aware that there is a requirement to have 2 internal doors between a kitchen and bathroom - but was thinking I could knock through from the kitchen, into a small utility area, then a door going into the old toilet and coal shed -which would become a downstairs shower room or bathroom.

Any thoughts?

Many thanks in advance

Sam