When you look for a DIY conservatory you should be looking for a company that provides all your glazed panels including the roofing panels, doors with locking mechanisms, all the connectors to attach the panels to each other and to your base or wall, a full guttering kit to ensure proper drainage and a full fixing kit.
We know that this sounds like a lot of kit and looks complicated, but if you have put up a self-assembly shed, or have converted your garage to an office, a bespoke self build conservatory shouldn't be that much of a problem. As with all good DIY work, you need a good set of tools, some patience and the practicalality to understand that this isn't a one man job and you will need a second pair of hands for some of the time.