I put my tins in with Metal in the recycling - old screws and coathangers etc go in there as well.
We havea doorstep collections for greenstuff, jars/tins/glass/plastic bottles, and paper, but I have kept an eye on the various skips up at the recycling centre (I sound very virtuous, I know!) and now collect metals, batteries, small electrical, and silver foil here at home in 2 separate bins, which I heft up to the tip every couple of months as they fill up.
Yes I share your concern about polystyrene but for packers, it's very light and it can be shaped to fit the item.
What annoys me more up at the dump is people blatantly dumping cardboard, wood, etc., in the non-recycling domestic waste carts - there is often an operator on hand to redirect them but some people just chuck everything away without thought. Our recycling centre is only a short walk from cart to cart - I can't believe how these people can not be bothered to do their bit!