Stay away from SD Realm - we had a total disaster.
Things were going really well in the beginning Last summer and everything seemed to be on schedule until all hell broke loose and we were stranded during winter with a leaking roof and broken bi-fold doors no real kitchen and freezing house with a toddler.....(Supposed to finish end of August and we are STILL - in May 2012 - trying to complete unfinished decorating now with the help of other builders). One of the worst experiences of my life and I have never been that close to depression!
The guy who runs it (Daniel) seemed oh so professional at the beginning with daily updates and always replying emails and taking calls. He then disappeared. My son got a chest infection from the cold and dust, I lost a stone. His tradesmen complained that they weren't paid and walked out. We wanted a loft conversion and a side extension - we got both in the end, thanks to other builders we are happy with the result but I would NEVER recommend the Co and regret doing so in the beginning. Hope none of you have a similar experience.