Hi Shaz,
I had my u/s last year. You need an empty bladder and its a bit weird having the probe inside you, but its interesting seeing all your parts on the screen. It didn't hurt at all.
My HSG was fine, a bi awkward and it was a sharp pain when the dye was injected, but I've had much worse af pains. I had a bit of cramping and bleeding afterwards, but, again, nothing that needed pain relief. I went straight back to work.
Good luck
Windy x