I have inlcuded some pics as they may explain it better.

This is the split charge relay on the starter battery, as far as i can make out it is wired to both batteries, earth and alternator signal wire.

This is the bit i dont understand, the leisure battery is connected to the starter battery by a thick 8mm cable on the positive. Is this normal as i thought the batteries were supposed to be seperate apart from the charging to prevent the starter battery going flat?

This is the leisure battery.
I have checked the leisure battery with my meter and it goes up to around 13.5v with the engine running then down to just over 12v when engine off. So the split charge seems to work.
Sorry for all the questions and long post but im going away in it for the first time this weekend and dont want to be stuck with a flat battery lol.