As you see, Case 3 heavily relies on the defintion home. If the owned flat in the third contry can be considered a "home" for the purpose of SRT, then Case 3 doesn't apply.
have one or more homes in the UK at the start of the tax year and at some point in the year cease to have any home in the UK for the rest of the tax year - yes, after 1st of June the rental agreement ...