Slow cookers r a life saver for this .literally bung it all in and leave it on low .most supermarkets even do the "prep" side of things for u aswell like prepared fajita packs ,or chopped veg etc.
Other than that a cooked chicken or 2 would go along way for u , doesn't matter if u eat it cold or reheat in the microwave,use it in wraps or bung in with some sauces and microwave rice to make a curry ..the list is endless.
Another idea would be to batch cook on a morning/afternoon/eve u have free I'd cook up massive sheppards pies,lasagne,chilli's etc and then all u have to remember to do is get out of freezer and pop in oven when u get home . X