It's annoying to be without a drink but with cold food you have an option to wait for the drink to arrive without affecting anything, whereas it doesn't work with hot food.

Since there is no 'choice of meals' on these flights it's faster to distribute the meals first and then get onto the drinks (which can take a while to do), especially as the drinks can be served in a plastic cup late in the flight if needed so that they can keep the drink till after all the trays had to be collected.

Crew to passenger ratio is at the minimum level so it becomes pretty important to prioritise. If they are very over-crewed like you get on some airlines (I have had 3 crew members to 12 seats in F on some domestic flights in another country - of course, it's easy to do all the service then including a hot meal and multiple drinks) but that's not the case here, and over-crewing in countries like the UK with a lot of fare pressures (esp at LGW) and relatively high wages/fare ratio compared to some other countries would be unsustainable.