There doesn't appear to be anything in the legislation to indicate that the candidates cannot vote for themselves.
In the end, the answer may be arbitrary. Candidates for chairman need to be present at the meeting, since it is a statutory requirement for the elected chairman to sign a declaration of acceptance of office at the meeting. If this does not happen, the election becomes ineffective. There is thus no point electing an absent member.
If every candidate votes for themselves, the votes cancel out, giving the same result as if candidates were excluded from the vote. But if some candidates choose to abstain or vote for another councillor and others don't, the result would be affected. This would mean not all candidates were contesting as strongly as others.
On the whole, I can't see any justification for excluding the candidates from the vote, although they might as a courtesy choose to exclude themselves. Sorry that may not be as definitive as you would like!
