I buy rolled oats and add a few walnuts and half a grated apple and a few sultanas or other dried fruit. I cook that up to make a tasty porridge. I like sultana bran but don't buy it these days. I use weetbix in a couple of recipes but don't like it with milk as a cereal.
I make up my own bircher muesli about monthly, with the basis as quick oats and add linseeds I process myself, spelt puffs, quinoa puffs, some currants, flaked almonds, and some oat bran. I mix and put it all in a large jar. Use 2 tablespoons soaked in 1/2 and 1/2 kefir and almond milk or oat milk. You can really make up anything you want and it will keep for ages in a glass jar. It is yum. When you want to eat, stewed fruit can be added if you want. The sky's the limit really.
I have 3 weetbix for MY breakfast with 2T rolled oats, lots of cut up dried fruits, a little coconut, homemade plain Greek yogurt, 11 bottled cherries, 2/3 slices of tin peaches or 1.2 a tin apricot, 1/2 a diced banana, & blueberries, strawberries or raspberries if I have some. Oh yes & a small tsp of wheatgerm, almond meal, LSA, chia seeds & a tiny bit of dried diced ginger. I soak all the dried stuff in fruit juice overnight, then add a little more juice when I'm about to eat it, if it's still to dry. At boarding school for 1 breakfast, I ate...(now don't be to shocked): 25 weetbix'!!!) I could have eaten a couple more, but I had to go to class! I wasn't good at anything at school, so that was my BIG THING that I did in my 4 years at high school! I doubt if it was ever recorded it anywhere though!