I would like a small bathroom extension how do I go about this?

I would like to build a small extension to my kitchen to house a bathroom and put my washing machine in there too. I do not seem to be able to find a builder that wants such a small amount of work as I wish it to be in hard blocks in order to render it when finished - the rest of the house has pebble dash .. which eventually I would like to take off ..do not know how to do this either. Any help would be appreciated.