Wrap Around or Side Return with Box? Help/Ideas please

[Rbuk711]

Hello,

Hope you are well. We are considering a few different options for a single storey extension of our 1930s semi (we're in the North West). Photos of rear of house attached for reference. 

 

Option 1) Wrap around. We would opt for a vertical steel to hold up the rsj that will support upstairs instead of the 940 pillar drawn on the attached floorplans as a pillar will be smack in the middle of our worktops!

 

Option 2). Side return along the full length of the house, PLUS box extension adding space to the existing rear opening where we currently have french doors.

 

Ultimately, I want to know:

a) if option 2 will be considerably cheaper than option 1? 

 

b) opinions on cost of both options (understandably builders are very ball park about prices on this; however I don't want to put option1 through planning to later find out its out of budget!)

 

Many thanks for your help!