This question crosses boundaries between employment law, the law of contract and the national benefits system.

Since you are not an employee, it is unlikely that you would be entitled to Statutory Sick Pay – however if you have only recently gone self-employed you might be entitled to payment if you were fully up on your NI class contributions until less than two years ago.

Alternatively you might be entitled to claim Incapacity Benefit. It would therefore be worth a telephone call to your local Job Centre Plus to enquire. For the future, you might consider taking out ill health/accident insurance to protect your income.