10. The assets of any business owned in whole or in part by the claimant if—
(a)he is not engaged as a self-employed earner in that business by reason of some disease or bodily or mental disablement; but
(b)he intends to become engaged (or, as the case may be, re-engaged) as a self-employed earner in that business as soon as he recovers or is able to become engaged, or re-engaged, in that business,
for a period of 26 weeks from the date on which the claim for housing benefit is made or, if it is unreasonable to expect him to become engaged or re-engaged in that business within that period, for such longer period as is reasonable in the circumstances to enable him to become so engaged or re-engaged.