I posted the latest cycling UK advice previously and suggest that you read it
https://www.cyclinguk.org/article/coronavirus-qa-it-safe-cycle
I think that the relevant bit for you is:
"Roger Geffen (RG): The answer we received from PHE suggests that if your chronic condition is relatively mild, you can follow the same advice as that for the over 70s."
The advice for over 70s which also applies to you is
"H: Yes, but with
particular caution (my bold). The latest advice is to remain at home for the next twelve weeks to protect yourself from infection.
Public Health England (PHE): If you're from a vulnerable group but feel that you need to take a walk or go for a bike ride, choose a route where you are unlikely to meet any other people or take your exercise at a quieter time.
This will reduce the risk of exposure to other people. Exercise at home or in your garden is encouraged where possible, for example on a turbo trainer or an exercise bike if you have access to one.
Tissue use and hand washing advice is as above."
PARTICULAR CAUTION is what I have taken note of. Therefore I will go out when not many other people are likely to be out.