So I held off donating, but decided to have another go a few weeks ago. I actually wanted to try and donate platelets, but was told that they weren't taking platelets from females anymore ... something about previously pregnant females having antibodies or something .... I can't remember why!
I donated on a Thursday and went away that long weekend. I did feel extremely exhausted at certain points, including when I was driving back on Monday. Reading a little bit on the internet and I decided to drink Powerade to power me back on track.
I also read that donating plasma may reduce your levels of antibodies and make you more susceptible to falling ill. I'm really not sure if I'll donate again.