We had it done a year ago. I chose four local sparks from the official electricians' website which is the safest way to do it. Only two were interested. Apparently it is more lucrative for them to do industrial than domestic. It took two weeks and cost £5k with the finishing vertually ready to decorate. We had it done when we were out of the house on holiday. We are London'ish, but a relative in Liverpool got it done for half that.