All pipes, rainwater, SVP, etc have to be modified and brought out. The Electrical box is also extended out along with window cills, etc. You also need to consider all external items which are fixed to the walls like gates, clothes lines, satellite dishes, TV aerials, etc. You can't fix these to insulation later so want to allow grounds same way radiators internally need support. It looks like you have wet dash too which might need a coat of plaster to create a smoother more level base for the external insulation. You don't want air pockets behind the EWI. It's a big job that needs a lot of consideration.