The back door when we bought the house was an aluminium sliding door that had seen better days. It did not lock properly and could be lifted out of its runners. Air whistled through the gaps and the aluminium and thin glass let heat out and cold in.
The idea is to slowly clean up and renovate the outside area under the pergola. It is very sad with mismatching weatherboards and the outbuildings are in poor order.
Replacing the back door would be a good start. Fortunately a pair of good French doors came up on Gumtree not too far away. They would fit with a bit of work and would be alot more secure and windproof.