Glucose test questions...

Hi ladies, let me start by saying I'm in the UK specifically Wales not sure if that makes a difference but thought I'd get it in there. I have my glucose test on Tuesday. Iv been told to fast from 10pm the night before 😔 and allow 2 and half hours for the appointment. So I'm just wondering what exactly happens. I'm going to have rest of my 28 week bloods done there too, well at least I was told I could if this appointment happened to be before my next midwife check up which it is. Also how long do results take? Thanks in advance.