Everything I have read - no!
Please reconsider all possible alternatives: Monday to Friday lodger (see Google), take in students from overseas, (see your local paper or language schools in towns near you), a full-time lodger (you could still have a lot of privacy (ask Answerbank posters for their experiences), check with Citizens Advice that you are getting all the benefits that you are entitled to.
Downsize to a smaller home/one bedroom flat/studio flat.
Use Equity Release as an absolute last possible answer.