If you are doing heavy works on the place then I'd go nuts with the insulation whilst you've got the window of opportunity to do (similar to Jonny, above). You won't want to come back to revisit that in the short-mid term as it's so disruptive.
As you are mid terrace, your job here would be slightly easier.
Then fit whatever works for you regarding heating; gas / elect / ASHP etc.
If the house itself is pissing heat / energy away nothing is a 'green' solution so you might as well fit gas, make your life easy and yolo. You can then revisit in five - ten years time.
If you are doing heavy works on the place then I'd go nuts with the insulation whilst you've got the window of opportunity to do (similar to Jonny, above). You won't want to come back to revisit that in the short-mid term as it's so disruptive.
As you are mid terrace, your job here would be slightly easier.
Then fit whatever works for you regarding heating; gas / elect / ASHP etc.
If the house itself is pissing heat / energy away nothing is a 'green' solution so you might as well fit gas, make your life easy and yolo. You can then revisit in five - ten years time.