You can make the food transaction and ask for a receipt. The receipt comes off a bluetooth printer which isn't quite as slow as the main Tourvest POS but you can tell crew are a bit relieved if you say "no receipt needed".

The way I would do this (well, as a total abstainer this isn't what I would do, but anyways) is by getting the main meal, presenting your card, and asking for a receipt for expensing. Then either use a second card, or better still use Avios to buy the alcohol. You hardly need a receipt for the Avios transaction since you'll get a line on your BAEC statement a few days later, and if it is wrong then it's relatively easy to challenge.

If you can use contactless or Apple Pay that greatly speeds up the transaction (Avios is actually a bit clunky). If both transactions are with contactless, then the fact that one has a receipt won't slow things down by very much.