Cavity Wall Insulation Problem

[Always Problems]

I am renovating a house for renting out. It is a semi-detached so obviously it has 3 external walls. But at the back of the house there is a large conservatory which is the entire width of the house. I rang a C.W.Insulation Firm for a quote and mentioned the conservatory and they said that I would have to pay for scaffolding over the conservatory. Not that I know how they would be able to span 20ft.
Anyway should I consider just having the other 2 walls insulated. After all the lower half of the 3rd rear wall where the conservatory is, allready has protection against the elements by having the conservatory so the only area which would be un-insulated is the top half of the wall above the conservatory.
Thoughts anyone.

[mind the gap]

I am renovating a house for renting out. It is a semi-detached so obviously it has 3 external walls. But at the back of the house there is a large conservatory which is the entire width of the house. I rang a C.W.Insulation Firm for a quote and mentioned the conservatory and they said that I would have to pay for scaffolding over the conservatory. Not that I know how they would be able to span 20ft.
Anyway should I consider just having the other 2 walls insulated. After all the lower half of the 3rd rear wall where the conservatory is, allready has protection against the elements by having the conservatory so the only area which would be un-insulated is the top half of the wall above the conservatory.
Thoughts anyone.

Is it practical to insulate and dryline the interior surface walls of the external wall above the conservatory? It will take about 5 cm off the room's width, but would be very effective in insulating it. And cheaper than all that scaffolding. I would hav nightmares of the contractors dropping stuff off the scaffolding through the glass of the conservatory, as well.

[JK0]

I would pay for the scaffolding. Most of the cost of CWI is subsided by the energy companies nowadays, but I don't think you get this subsidy twice, or for interior insulation.

Alternatively, if you are going to redecorate upstairs, why not have the CWI pumped in from inside?