In reply to minimike:
Ignoring the question in traditional UKC fashion. Are you absolutely sure you want a conservatory? if so, are you ready to pay for a good quality glass roof? I've yet to experience a conservatory that isn't far to hot in summer, far to cold in winter and only really comfortable for a few weeks every year.
A conservatory is often seen as a cheap way to get extra space while dodging many rules of building control regarding insulation and R-values which you'd never be able to achieve at any sensible price building a room with so much glass.
The reason they dodge these rules is that they aren't supposed to be centrally heated and are supposed to be isolated from the main house with a external quality door. These points are often either ignored by the builder or otherwise the changed afterwards (radiators fitted and doors removed) when the owners realise how cold the thing is and how annoying the doors are.
Our conservatory is a bike shed at best, and not a very secure one because everyone outside can see the bikes and I'm sure the ~50 degree C it gets to in the summer isn't good for bike gear.
