Optimate and BMW chargers will plug into the accessory socket. But canbus wasn't coded to allow for battery charging and the charger needs a clean connection to work properly.
Most reliable option is an ordinary Optimate and connect the supplied charge wire direct to the battery. Then simply plug in the charger. No fuss no bother and no canbus hassle.
For accessories it's easiest to fit your own fuse box fed direct from battery, connected with a relay triggered by the canbus. That way it all turns on and off by canbus but has no power/current limitations.