Any input from the leccy guys very much appreciated.

(52 plate 3.2)
Travelling home in the early hours, so all lights on, goes to give it the big one when the battery light came on. Pulled over immediately to check the aux belt and that was fine and the car was running fine at this stage.
My next move may have been very careless on my part as, due to the road I was on not being ideal for waiting for the AA from a safety point of view, I decided to carry on to somewhere safer. I did actually manage to get it the remaining five miles home but a series of issues took place along the way, hence why I'm annoyed with myself for not just waiting.
In order of issues:
Battery light comes on solid, no flickering, just on nice and bright. Aux belt is fine.
Continue journey and dash lights start to get dimmer and radio goes off.
I touch the brakes and the TC, Spanner light and Airbag lights come on and stay on.
The rev counter and speedo are stuck at 2000rpm and 60mph respectively.
I know the old girls dying but she's nearly home, just another mile to go.
I lose the o/s xenon, closely followed by the nearside xenon but I'm now in the heavily lit town.
I pull into my drive and the idle rpm rises to 1000rpm on its own.

Switch off and go to bed.
This morning I ran some checks.
Engine off as I left it last night = Battery reading across terminals is 11.75
Battery wouldn't turn engine over so I left it on a mains charger for three hours (terminal clamps removed in case I did it more harm).
Retested since charging and I get:
Rev counter and speedo now back to zero as normal
Engine off, across now connected terminal clamps = 12.24
Cranking 'pull down' = dropping as low as 10.15
Battery terminals with engine at idle speed = 11.51
Battery terminals with engine at 2000rpm = 11.4
Battery terminals at higher revs = 11.4
Didn't get a chance to do the 'lights on' check as the engine died at that point. Battery is now flat again.

When I'd charged the battery I did try the xenon's and they are both working again so I'd imagine that everything was trying to run direct from the battery power last night.
Assume this points at a replacement alternator and a new battery. Just hope that I haven't fried anything else by getting it home.

Any input very much appreciated as always.