I am a Premier Executive flying from HNL to London on December 3rd and was wondering what lounges I am able to get into.

Currently, I am waitlisted for F for the HNL-DEN leg, and am booked in NF for the DEN-ORD leg and NC for the ORD-LHR portion. All of the flights are UA.

Are there lounges that I am able to get into in DEN and ORD as I wait for the next flight? Also, since the total travel time is nearly 24hrs, is there a place that I can shower when I arrive in LHR? Thanks.