National Timber Buildings provide an excellent service. They were willing to give my builder clear instructions on the 'phone when we were uncertain about the precise base dimensions and on the day of erection they were fast, independent and uncomplaining about the 20 metre uphill carry to the site. The completed shed is excellent and is the envy of all my friends. One suggestion: you should offer a premium service to install M6 bolts at 130mm for the hinges and M6 bolts at 75mm for the door to provide better security. This would have saved me a couple of hours of work post-construction.