The Equality Act 2010 defines someone as a disabled person if they have a physical or mental impairment which has a long term and substantial adverse effect on their ability to carry out normal day to day activities.
A disability may include progressive conditions such as HIV and cancer, mobility, sight or hearing impairments or mental health issues such as depression.
In considering whether you have a disability you should not take into account the effect of any medication or treatments used or adaptations made which reduce the effects of an impairments (other than glasses or contact lenses used to correct a visual impairment)