I personally would follow Norms guidelines for the first two weeks as closely as possible, and then add in things like milk and cornflakes. Things like omlettes and maybe a tiny amount of full fat unsweetened greek yogurt, bacon or chicken sausage, etc..for breafast with maybe avocado and veggies??
Lactose free milk is honestly just a weird food. If you suspect you are lactose intollerant i would take out that kind of dairy altoghter for a while. Also, do the corn flakes contain added sugar? That would be of concern. Why not opt for a nutrient dense breakfast, like some of the suggestions Norm makes, at least for two weeks and see how it goes. Corn flakes were a convenience box food invented around world war two.Honestly our health as a country has gone down hill since we started eating so much processed food. Stick with the basics for a bit!!