When you have decided on the style of conservatory that you want, there are a number of things to take into account before going much further. The most obvious one is do you have any height restrictions where the conservatory will join your house.
These would include upstairs windows, the roof eaves, external cladding etc. If the height is ok for your house look out for other items. You do not want a manhole cover in the floor of your conservatory and as they are normally situated on the rear of a house, what about soil pipes, drain pipes, boiler flues and the like. These can be difficult if not impossible to move.
I you ask us, we can send you a guide to designing your DIY conservatory which will cover all of this and more.