I've been ill since yesterday as in, being sick however today I feel a bit better and a little bit hungry. I want to avoid food which will make me even worse. I know I shouldn't eat fatty or salty food but would soup be ok?
As a rule, something dry and non-fatty or non-greasy. If you've been very very sick then it's worth drinking something that will replace the salts you would have lost through dehydration. Something like Diralyte (not sure about the spelling) which you can get from most pharmacies, or even something like Lucozade Sports (the non-fizzy variety). Drinking plenty of fluids is always a good idea, water and squash are great.
Dry biscuits like rich teas or digestives are good. It takes your stomach around a week to totally recover from a bout of nasty illness, so be gentle to it for a few days! Avoid things that are fried etc until the weekend!