NumbsMet etc—very sorry I haven’t caught up on the thread yet so if it’s been mentioned...well...
Good fats can come with butter, olive and other oils, mayonnaise, but don’t forget about meats.
Seek 15-20% mince rather than 5% lean. Seek pork belly. Seek oily fish such as mackerel. If you get tinned tuna, get it in sunflower oil and then add a mayonnaise brand that is naturally low carb such as DeLouis or Hellman’s. (then for crunch add chopped shallots or water chestnuts or cornichons, I’m my expert humble opinion.
Make up a batch of the tuna and plop it over raw spinach leaves, and then add a French vinaigrette or EEVO/red wine be age/salt&pepper/Dijon on top of that.
It’s how we get great fats in, plus nutrition, plus you can always add hard boiled eggs or cucumber or cherry tomatoes etc if you like.
This combination might be too high fat for the calorie part of this first week, but it ticks a lot of boxes for future meals.