Need to swap bathroom and bedroom

[Qwertybynature]

We've recently bought a house and want to change the layout of the bathroom and one of the bedrooms (i.e. swap them around). We have not taken on a project like this before. It would mean the bathroom is at the rear of the house instead of the bedroom. Both rooms have external walls.
Who do I need to get in contact with to plan it? Would a builder be able to help with planning and design? Both rooms are part of an extension on a Victorian house so if we take both out the space it leaves is essentially a blank canvas.

[SwedishEdith]

A builder should be able to do that.

[Qwertybynature]

Thanks SwedishEdith