Originally Posted by
DYKWIA
Emirates should tag the baggage all the way to Chicago. On arrival at LHR, follow the 'connections' signs. You'll then go though security, and be back airside.
No need for immigration or customs.
This will only happen if the entire itinerary is on 1 ticket, which from the OP's post, I can't determine. I recently opted not to transit through SYD in Australia even though I was arriving on CX and departing QF from the International Terminal - just appeared too risky. If something goes wrong, you can't get visa on arrival. So, if you officially need a visa, as it appears, I'm not sure I would want to chance it. But that's me. Good Luck, OP!