Illness/critical illness insurance
Given that you are self-employed, you may consider it prudent to obtain insurance against the risk of illness. This is particularly likely to be advisable if you are not supported by another member of your family or you are the main breadwinner. The purchase of a house with mortgage finance and the birth of a child are often instances which cause self-employed barristers (among others) to consider insurance against illness. Advice can be found on the Citizens Advice Bureau website.
The Barristers Benevolent Association
In particularly hard times you might consider contacting the Barristers Benevolent Association. In times which are not so hard you might consider donating to the BBA.
If the donation is Gift-aided, a self-employed barrister who pays higher or additional rate tax will be able to claim the difference between the rate they pay and the basic rate of tax on the donation. An employed barrister who pays under Payroll Giving will receive tax relief whatever the rate of tax they pay. See generally https://www.gov.uk/donating-to-charity/overview.