Nick would have wandered down to Hogsmeade by himself with what was left of his pocket money. He would have waved to Geoff if he saw him but steered clear otherwise, not wanting to disturb him on his date.
He would have stopped and said hi to Flissa and Kat if he ran into them. Probably would have even stopped and chatted Zoe up a bit as well. Mostly he would have just wandered around and enjoyed a day of not being at school.