Tenant missing from property - left belongings

Possession - Section 8 and Section 21

Hi everyone,

I have served my tenant with a section 21, which expired on 11th Septermber. My tenant doesn’t reply to texts or take phone calls or reply to all the letters I post through the door. The property is an 11th floor flat so it’s impossible to see if anyone is home unless you access the flat. I have accessed the flat recently (having given prior written notice) and it appears from all the post, etc, that he has not been home for several weeks although all his furniture and belongings are still there. He has therefore not vacated as per the section 21. I have now tracked down his parents who have told me he’s moved to Coventry where his girlfriend lives (tenancy is in Hull!). As yet they have not given me his new address. How should I legally reclaim the property and if need be remove his belongings/furniture. At this stage I cannot tell whether he intends to return at any time to either continue living there or to collect his stuff and move out.

Thanks