
I've fitted a cat flap in a conservatory by changing one or both of the small glass bottom panels in the doors with a solid panel, any conservatory company could supply you with a panel to match your conservatory. Then fit a standard dog/catflap in to the panel making sure that its suitable for a 25 mm thick panel, any local tradesman could do this for you. Unfortunately I'm rather a long way from Bicester, although the mention of it brings back many happy memories of my days at St Davids Barracks, Graven hill.
Robert