Treasure it for the gem of a 1940s/50s home it is, complete with glorious wrought iron work. Suggestions have been made as to how to boost the height to meet current building codes. You will regret updating the exterior for what is likely to be a one that will date quickly and be higher maintenance . It is only a matter of time until such homes are as treasured as Victorian terraces or Californian bungalows. It is an icon of its time. Accept it for what t is. Why make your house look like a fashion victim of 2019, when it stands in almost the full glory of its original period? It will also save you a fortune too! But yes, minimise the concrete! and add a garden that refects the period the house was built. Roses if you like them, with maybe a magnolia or crepe myrtle feature tree but for lower maintenance try some architectural and ground covering succulents. You could also go with edibles like feature citrus and olives for a Mediterranean feel.

I don't know why people want to invest in render. If money limited I would always first go with replacing Windows with energy efficient Windows which increase natural light and maximise views or garden trees from interior Plus I'd remove brick fence in front of door as houses where you can see front door always look so much more welcoming as upgrade of workers cottage on these latest dilemmas shows

I like both ideas, however think it's good to consider the practical as well as the aesthetic you are wanting. Consider your space and picture how each would look in the space you have. To throw a few more ideas at you, here are a few pics I just found on Houzz. There are certainly some very cool designs happening in the architectural world. Just decide what moves YOU and to heck with what a builder thinks-it's not his house (even if he is a relative). :)

Budget? Glass is expensive, looks great in certain contexts but similarly can be not that great considering the cost unless it's done super well. In your case because you have a 4m high drop you'd need a handrail either way. Unless it's consistent with the rest of the design/finishes probably other options arguably a more appropriate balance. Define your needs/function and balance the options to a viable cost. I'd agree with oklouise, something along the lines of existing updated to code probably the best balance for aesthetic, function, maintenance and cost.