Preparing for winter

Hello all, hope you all had a good Xmas.

I'm a newbie and have bought a Lunar Clubman SB

I know that I have to drain the system but not sure how to do this. I have found the drain tap next to the boiler and have switched it, but are there any other things I need to do? Should I have the pump running so that water pumps through the taps? 

Also want to ask if the leisure battery charges itself when plugged into the mains at home? 

Thank you in advance.

Carol