What can my daughter apply for

Hi there, my 18 year old daughter has had fibromyalgia for a couple of years but has also recently been diagnosed with persistent postural perceptual dizziness. She has had to give up work as it was very stressful and couldn't concentrate and her consultant said stress will make her condition worse. She's currently working out her notice on a sick note and will only receive statutory sick pay. So I'm wondering when we can start applying for any benefits and which benefits, thanks.