Thank you very much JAXBA, most helpful. We fly back into LHR - will that change the return menu, do you know? We're due to take off at 21.45 so the food would need to be worth staying up for! Otherwise we'll dine in the lounge or airport prior to boarding.
A bit out of date now, however, I posted my menu and pics for BA274 LAS-LHR for January here -->
https://www.flyertalk.com/forum/35932070-post105.html
As
mikeyfly says, the LAS lounge is a tad basic for food, bags of crisps, some carrot sticks, and soup - nothing substantial.