I found their mussels in the seafood aisle (in a cardboard box, cooked in wine) were great as tended to have a long date on them - we use them either with skinny fries as "moules frites", or throw them into some spaghetti/linguine pasta as a different type of dinner.
If you have ANY freezer space, suggest a multi pack of individually portioned meat/fish - they are vac packed inside the bag, and very handy but can be easily slid into small spaces in freezers. I know there is chicken breasts, turkey breasts, salmon darnes and possibly others.
Is the weather nice around you for a few days? Could some nice BBQ stuff be useful? Or their spatchcocked chickens to throw in the oven, serve it with a nice salad bowl and a good crusty loaf of bread, maybe some coleslaw on the side?
Lots of their sausage rolls tend to have reasonably long dates - the bigger pulled pork types especially - they could be good for at least a week and nice for lunches.
A nice dessert if you want a treat - not a creamy based one (unless the éclair stack has a good date on it) but maybe a tarte au citron or similar? Or their key lime pie, or chocolate tart?
I like to nibble the puff pastry cheese twists with a glass of wine some evenings - they are usually in the biscuits/crackers aisle and have long dates. Then end up buying white chocolate cookies, and the fruit oatie cookies, shortbread biscuits, and Viennese biscuits while I am there.....
Some of the ready meals can also have a number of days - so if you suggest a few that you like (maybe even just themed like GastroPub, or "Italian but not the lasagna", or "Chinese with egg fried rice", or "Indian including a starter", or Thai) and ask for maybe a couple of nights dinners with as long dates as they can get - I've got them with 5/6 days to use them plenty of times.