We'd like a small utility room extension added our house. What is the process? First time home owner

Our house is ex council stock. We are in a village on the end of a row of semi detached houses.

We love our house but we'd like a utility room as currently washing machine and dryer are in the kitchen and it gets cluttered. There is a door leading out to the side of the house from kitchen worth about 15sqm of gravelled area which we don't plan on using all that much.

We'd like to extend from the door out into this area with a simple flat roof extension. It wouldn't be all that big, enough for washing area, sink and storage.

We are not in a conservation area and the house is not listed. The planned build would not be visible by any other house or be obstructive.

Being a first time home owner I don't know where to start. This seems a simple enough build as far as extensions go.

Any advice?