I usually disregard Daylight Savings Time when I say times.
irc.uk.mibbit.net
#Bay12DH
#Bay12DHooc
Go to Mibbit.com
click the Go Straight to Chat button.
When the chat app loads, click the 'Server' button next to the bar with the drop-down menu.
A new bar that you can type in should appear, and the bar that had a dropdown menu should be grayed-out.
In the new bar type irc.uk.mibbit.net.
In the bar on the left below that, type in your Bay12 Username, or anything else you feel like typing. It doesn't matter.
In the bar on the right of that, type in #Bay12DH,#Bay12DHooc . You can copy/paste that, and the server name.
OOC means Out Of Context or Out Of Character, just so everybody is sure.