Advice on what to do with the render on my house

It makes sense if you have a number of issues and concerns to get the whole lot redone, particularly if you are having the windows done. If you strip it back and render with modern mesh etc is should see you right for a fair few years.

In this case if you don't like the dash and also having the cracks I'll suggest also to insulated fallowing by adhesive and mesh and to finish with a nice top coat. Then all you issues will be sorted. Hope this helps.

The best solution would be to take all loose blown render off investigate the cracks to see if they are structural if not then scratch coat with sand and cement to the level of rough cast then E M L screw and plug fix all area then either rough cast or flat render area

You should consider insulated render! This involves fixing insulation, thickness depending on soffit depth can be from 25mm upwards and allow 5 mm for the thin coat render. As you are fitting new windows you can allow for the depth of of the insulation and render with cills to suit. Unless the render is completely boast ie not attached to the substrate, leaving it in place will be fine and save on removal costs. The insulation is fixed by fixings attached thru the render into the brick/ block work. Check it out on u tube and see previous work before you hire! Shaun Murray