I had a long wait for my gallbladder surgery so I am fully sympathetic! My go to dinners were:
Roast chicken with new potatoes and gravy (cheap gravy brands are lower fat). Obviously no skin eaten.
Loin cuts of meat are usually very lean (thats why we usually wrap in bacon etc!). I made a passable lamb stew
5% mince cooked and drained into usual bolognase recipe but pan spray for softening onions and no cheese obviously
Prawns with lemon and salad was a boring yet easy lunch. Tinned soup with bread (lentil and bacon was most tasty low fat option imo). Skinny latte or mint tea at costa. Watch them like a hawk though as they don't take the skinny seriously and just use whatever sometimes.
Stirfry made using pan spray and sweet chilli sauces are usually fat free
Lloyd grossman curry sauce -bhuna I think- was low fat and I poured off visible oil at top of jar. Cheap naans from tesco are low fat.
Poached egg white with pan spray mushrooms on toast I used to imagine I was a fancy LA type
Could eat white fish, usually no oil to pan fry or a bit of pan spray then dab any oil off with kitchen roll.
often you have to stick to cheaper food. Eg plain white bread lower fat than lovely seed brown bread. I used to buy lots of sourdough as it was a bit more interesting with just jam on.
Treat wise there are lots of options really, jelly, meringue, sorbet, haribo. A dietician friend made me a fat free cake once which was apple puree and banana puree in place if egg yolk and butter but I never managed to make a decent version.
The other thing that could set me off was being hungry or eating too much, so little and often.
You will find your threshold, for me anything over 2% was dangerous.
Good luck! 