PAT is Portable Appliance Testing. It means someone has to plug an approved testing device into your equipment (amp, electric drill, whatever) and issue a certificate that says it's safe to use.

The session is paid for (sort of - the money they give us pays for the hall we use for our Irish music group on Saturday mornings). The reason for the amps/mikes is the club we have the session in is an acoustic nightmare, and no-one outside the circle can hear us.
The current thinking is, that the tables we use will be reserved for us, and we will suspend a microphone from the ceiling over each table. The mikes will be connected to a mixer, the output of which can be fed into the amp system they use for the big TV set. So the speakers are already there, we just have to figure out a hookup.
However, this means that someone will have to be driving the mixer - to shut off the mikes when a tune has finished so our conversations aren't relayed across the hall!
The session, just to clarify, is not a "circle" where everyone takes turns (like paltalk), there are maybe 15-20 musicians all playing at the same time.
I am gainst the idea myself - when the commitee voted, my input was "find a pub with better acoustics". But that's committees, and the music group needs the money to keep going. We're stuck between a rock and a hard place, I reckon!