OK, they are only phone photos but I think you get the idea. No disconnecting of the battery required.
Here you can see the fixed cabling in position. The positive terminal I just bolted onto the end of the thread that was fixing the positive side clamp in place. The negative terminal screwed onto the main earth point behind the battery. No disconnection of the battery at all.
In the middle of the battery (next to the ECU) you can just see the plug connector with it's cover on

Here's a close up of the plug connector that stays in place, with it's weatherseal cover off.

Here's the actual charger (that is usually in the garage (just shown on the engine for clarity). And behind it you can see rolled up the 2.5m extension cable. Near the charging plug, you can see the yellow female end that clips directly on from either the charger itself, or the extension cable if you have it.

Finally, here's a close up of the two sides of the charging connector.

Hope that's all clear. Don't forget it does also come with crocodile clips so you can use them if you don't want to do a permanent charge point.