I think the people jumping on the OP are being a bit too bullish, here.
Kids out playing football, cycling around and generally being kids are fine. That's a fact of life and general noise that we all have to put up with.
Kicking footballs AGAINST your car, garage door and general property is not on, and indeed the repeated banging and worry about what's being damaged will drive you absolutely insane.
To the OP: it really depends on whether these are "decent" kids in a nicer area (cul-de-sacs are generally OK). If they are, just head out and give them a friendly word asking if they could try not to hit your property with the ball, as it could feasibly cause damage.
If you just get lip back, or it doesn't stop, you'll need to make a diary of events (including every "impact" and invasion of your property to retrieve balls) and report it to the council with a view to getting a "No Ball Games" sign put in.