AC should be able to interline your bag through, but the problem may be the length of the connection, though I have had bags in transit for more than 12-hours at LHR. Just show AC agent your onward ticket, and when you check in for your LAN flight, show them the baggage checks from AC so they can confirm your bags are there and will be boarded with you.

That's a long layover, but you should be able to stay airside. I have also read that LAN sells day passes for their Lounge, so this could be an good way to pass the day: great Chilean wines, tappas-like food, TV and reading material. Not sure if they have showers though, or sleeping rooms as CX and SQ have at their home terminal lounges.

Thanks, davistev, for the update on the visa charge. It is valid for multiple trips and expires when your passport expires, so it is best if you have a relatively new passport. Upon discovering this charge on my first visit -- it is not mentioned in any guidebooks I have read -- I had to scramble to convert a number of currencies into enough US$s to pay it. I generally travel with a few $10-equvilent units of left-over bills from countries I have visited. I only had US$20, a couple of UK£ notes, and some HK$s and SAfrican Rand. Was able to scrape together enough, was escorted into the Customs Hall to a Currency Exchange kiosk, and got enough US$s to make it. From then on, I have always had US$100 in various sized-US bills in my travel wallet for such little emergencies.