Basically: Bangers and Mash, as a pie
This meal can easily be prepared in advance (just add 15 minutes to the cooking time if you're pulling it out of the fridge), and doesn't require too much prep (the majority of the time really, is waiting for the spuds to boil)
You don't need to use the best, most expensive sausages, as they're being cooked in other flavours, but try not to go with the absolute cheapest either as they tend to be a pain to cook