Hello, we like the layout of our current kitchen, but it's dated and we'd like to redo it. If we're just replacing units and appliances without moving anything, do we need a plumber or electrician, or just a kitchen fitter? Would we need a plasterer? How long roughly does it take to take out and refit a kitchen? And how much might it cost for new units in a 3m x 3m kitchen? Thank you!