UK Landlord Forum / Life

I hope somebody can help me.
I am not sure I can be successful if I hand a Section 8 Notice to my tenant.
My tenant initially requested to move out at the end of the AST in January, but on the last day of his AST lease, he decided to overstay without notice.
As AST agreement, each month I have  been invoicing for rent + costs (water, broadband, communal heating).
The AST agreement was through LHA, which added £3,465 for a 12-month lease (£288.75/month); LHA doesn't give any extra contribution for overstay.
My tenant's overstay caused a loss of £288.75 each month, therefore I have been adding those £288.75 as cost on the invoice since the 13th month; it's an additional cost and not a rent increase.
My tenant has refused to sign a new AST and paid partially the February's rent, not paying those £288.75. I believe a partially paid rent counts like an unpaid rent.Then my tenant didn't pay for the March rent.
I sent reminders and a Final Notice with traced email, all of them have been ignored.

If I hand a Section 8 Notice with two weeks notice, will the judge likely award me with a possession order?

I don't understand the situation you are describing.
When you say your tenant "requested to move out", did they give notice or just ask if they could leave?
It's not usual for a rental to be invoiced, who are you invoicing and who usually pays?
How are you losing £288.75 a month? Are you sure you're not earning an additional amount each month, which is not a loss?
How is the £288.75 not rent?

Is this a rent-to -rent contract? Same as JPK,I can't make head nor tail  of the arrangement you describe. Much more explanation needed please.