2 hours ago, Onoff said:

Something like this random off the web?

 

 

I wonder if the slightly setback detail would be a planning requirement.

Yes, excellent @OnoffThis is basically what I envisage, double right up the side, until level with the existing extension- from what I’ve learnt so far planning requires it to be stepped back  so not to give it a ‘terraced street’ appearance.

if I extend the hip roof as per drawing,how will  the ‘roof overhang’on the back end Tie in?  

 

a bit like this with a little valley at the Bach. 

 

A bit like this, but without the change of angle of the tiles at the bottom

 

Ideal, I’m finding it difficult to imagine how it’ll look but that helps somewhat. 
 

Time to look at the relevant pages to start planning the internal layout and heating system, if you’ve any tips/ ideas that I can implement then please let me know- open to every idea