External Wall insulation, good idea?

[Phr1]

Hi there, 

we are end of terrace, Edwardian house from 1910. External walls are solid. We were recently recommended to install external wall insulation on the long side wall of the house. This wall is fairly clean, no openings, just couple of pipes and a boiler flue. I quick check pointed to around £100 p. sqm. We have about 180sqm of a wall! That’s is big money and I need to add the cost of scaffold on top.
I don’t know if it’s worth it as other walls, front and back, will not be insulated. But my main concern is loosing the breathability of the wall and that I will have dump and mould growing as the moisture will be trapped inside. 
what do you all think? Is it worth bothering with this expensive job? 

[tonyshouse]

DiY if you can , 200mm eps and silicone or acrylic render will keep it vapour open , nice to do back too, front  could be 3D printed in a couple years time