anxiety

Not sure about anxiety, but I have been having a cup of hot chocolate with full fat milk and a banana ritually every night and it really relaxes me and calms me down for sleep. It might be more about the ritual than the actual foods though. Just build a ritual around bed time, like a hot bubble bath with a nice scented shampoo or something of the sort, or any other ritual you feel relaxes you.

For anxiety specifically, exercise is well known to be beneficial, so you might want to consider increasing your activity during the day. A 30 minute session of moderate effort in the early evening (not night) should be enough, like a brisk walk or something.

I've also heard vitamin B deficiency can cause anxiety, so might want to consider increasing foods rich with B vitamins.

As a last resort, our vet prescribed valerian root for our dog during storm season and said it's one of the few human remedies that is also approved for pets, and it works wonder for him. Don't take it on your own, ask your doctor and see if it's appropriate for your case and what would be the appropriate dosage for you.

I eat porridge at 8pm then I don't need to eat as I'm not hungry or craving

Is if fear of overeating or eating "bad" foods that's causing anxiety? Or inability to control nighttime cravings? Something else?
You don't have to be perfect, just dedicated! Over the first few weeks, you'll learn a lot about what works for you and where you might have trouble. In the beginning, work on consistently logging and learn which foods make you feel good and keep you full - maybe foods with lots of protein or fiber. Maybe higher fat foods. Start incorporating more of them, then work on accurately hitting your calorie goals (if you were shaky on this the first two weeks or so).

Plan out your day and pay attention to when you're truly hungry. If you're hungry in the evenings, maybe you can eat a little less earlier in the day and save more calories for dinner or an evening snack. If you think you're not really hungry at night, but maybe eating due to boredom, habit, or another reason, try a new hobby or light exercise to distract yourself?

Exercise has 100% controlled my anxiety. When I feel anxious at night (I have crippling anxiety coupled with night terrors and insomnia) I head to the gym.

I think there are 2 aspects to this problem - all of which the posters addressed. Food is a sedative- if you are feeling anxious you may have a craving to calm yourself down. Second, if you are at all like I am, I cannot go to sleep if I am hungry! So addressing general anxiety with exercise and then saving up calories to eat before bed are both great ways to start.