Why is no one just a little bit helpful for a change?
Well, I did try but I guess the advice wasn’t what you wanted to hear.
You’re obviously having a problem obtaining quotations from builders, otherwise you wouldn’t have posted your request surely?
You need the plans, schedule of works, specifications etc in place BEFORE you try to get quotes, otherwise, what are they quoting for? They’ll all come up with quotes on the back of fag packets for their own different interpretations of what you want.
Do things in the right order and employ a professional if you don’t have the relevant experience or time.
It WILL save you time and money in the long run. But then that’s not what you want to hear is it?! Best of luck.