Help with pricing

Happy weekend all ! 

I have been asked to price for a large school , but am struggling I did it 2 years ago as a sub contractor, and lost a load of dosh ! 

Its aprox 12 man days to do the inside and out ! 

I’m usually good at pricing locally but am struggling with this one ! It’s also glass only not the frames ! 

Thank you in advance 

Easy peasy, especially as you know how many days.

12 days at your ideal daily rate, be it "200-£250-£300" just charge what you want be earning.

Thank you mate !