Actually, I was wrong, its up to 26 weeks
'People leaving work are treated as having made themselves voluntarily unemployed. This applies if you resign, walk out or are sacked for misconduct. It doesn't apply to redundancy, end of contracts or on medical grounds (which can include workplace stress), or where you can show good cause (e.g. unfair dismissal).
Otherwise you are automatically classed as voluntarily unemployed. Unless you can disprove it, you face a sanction of up to 26 weeks without any benefit at all. Your case is referred to an Adjudication Officer who decides if it's fair and, if so, how long the sanction applies for. They will write to your employers for their side of the story. During this period you will be on no benefit, or reduced benefit in cases of hardship'
Hope that helps...