Planning fail! Can I make overnight hot cross buns with reduced rise

Hi guys!

i have a total planning fail. I wanted to make Dan Lepards Stout Hot Cross Buns (recipe here http://www.thefreshloaf.com/node/42306/dan-lepards-spiced-stout-hot-cross-buns) and it turns out my yeast was thrown out :( 

is there any chance I can buy active yeast at the supermarket tomorrow morning (9am, we’re in lockdown) add a little more, and rise for 8hrs instead of 12?

Thanks in advance!