The current guidelines from the Government concerning lockdown behaviour are here
Coronavirus outbreak FAQs: what you can and can’t do
Important are
16. I have a disability. What are the rules for me regarding travel for the purpose of exercise?
If you have a disability (for example, if you use a wheelchair) and need to travel a bit further to appropriate outdoor space where you can exercise safely (for example, a location that has accessible parking and level access), you can do so.
18. Can I exercise more than once a day if I need to due to a significant health condition?
You can leave your home and/or be away from your home for medical need. If you (or a person in your care) have a specific health condition that has routinely required you to leave the home to maintain your health – including if that involves travel beyond your local area – then you can do so. This could, for example, include where individuals with learning disabilities or autism require specific exercise in an open space two or three times each day – ideally in line with a formal care plan agreed with a medical professional.
Even in such cases, in order to reduce the spread of infection and protect those exercising, travel away from the home should be limited, as close to your local area as possible, and you should remain at least two metres apart from anyone who is not a member of your household or a carer at all times.