What will happen to my 2/3 pint blood donation?

I gave blood in the UK for the first time today, but around 4 minutes in had to stop because I felt faint and my vision started to blur. I was told that the bag was 2/3 full.

I appreciate they can't use this - and was told that I needn't worry as they may be able to send it off for research and so "still saving lives" etc.

I got the sense that this was a bit of a sugar coated lie and I assume it just goes straight in the bin. But does anyone know for sure? I appreciate it has been donated in some circumstances but if that's not the case most of the time I'd rather be told straight up. Does anyone know what the norm for the UK is?