BG Accept Scripts I have setup in my general use macros are as follows. I also highly recommend running the Stinkyqueue mod so you know which AV instance you and all your toons have been matched up for until they put in group queuing for AV in 2.4

Queuing for BG when the window is open for all characters
/script JoinBattlefield(0);

Accepting BGs that have queued up
/script AcceptBattlefieldPort(1,1);

I don't currently have one for leaving but thx to Keyclone's latest version you can just use the override DNP option and do /afk for all characters if you have to get out before the BG ends...