Hi Phil
Ctek do some good car battery chargers
I have a jaguar one, its a ctek one, with a jaguar logo on it
the jaguar kit comes with a socket you mount inside the boot and connect to the battery, through a fuse
if you connecting direct to the battery, just make sure it still has its vent tube fitted, it a tube from the battery that goes into the tyrewell and out the back panel, when you charge batteries you get a explosive gas, it should vent out the back panel, behind the bumper, just check its still there, as some people forget to put them back if they have had the battery out.
it ok to charge the battery with it still connected, make sure it a smart charger, not just a continuous charger, as it will just boil it dry
cheers
Joe