We used Lenny @ Hamilton Walters for ours last year and I cant fault them. You deal direct with the owners which just felt better for us. We had a few larger companies come and quote but they just wasnt personal enough for us. Price and time scales where comptitive and their references all passed the test as they were able to invite me to one of thier on-going projects not far from our house, where I was able to speak to their client and get their view and experience working with them too.
Hope this helps!