I hope you mean a battery maintainer (such as the CTEK) and not a trickle charger. There are two possible installation points. The first is under the hood/bonnet, right side. You will find the positive connection point under the red cover, clearly marked. The negative connection point is the nearby threaded post. But a much better connection place is in the trunk/boot area and there is a thread on this (look for "CTEK charger")...the two connection points are: negative - any bolt on the trunk floor, and positive: any point on the bar under the black plastic cover to the right of the main battery, the yellow wire connection point being the most commonly used for convenience. But any one will do.
While you are in there you can easily disable the start/stop system if it bothers you. Simply disconnect one of the leads on the small battery to the right, and wrap the connector for safety. Done! There is no negative effect, but there is the positive effect of eliminating the annoying stop/start (and the wear and tear on the starter).

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