I would advise you to eat 3 well balanced meals a day and to use the following guideline.
Porridge and fruit is a great breakfast.
For the other meals I would follow the 'plate division' idea.
A quarter of your plate should be lean protein such as chicken or fish, another quarter should be wholemeal carbs such as brown rice or quinoa. The other half of your plate should be filled with a variety of vegetables.
Have 2-3 snacks a day based around fruit and protein such as an apple sliced and spread with 1 tsp peanut butter.
Drink 2 litres of water daily.
Eat oily fish such as salmon twice a week.
Sugary and fatty and processed food should be a very occasional treat.