Cancellation of section 8 court hearing

Possession - Section 8 and Section 21

I filed a Section 8 with the court in December 2020. I have been given a date of the 19th of April when the judge will review the case and decide whether to proceed to a hearing.

The tenant has now served notice and I'm reasonably confident that they will be returning the property and keys etc this coming week.

Given the long delay between submitting to the court and the review date, does anyone know if I am entitled to my £350 fee back from the court if I cancel the case?

Assuming no to the above is the fee a cost I can legitimately / legally charge the tenant?

Is there any reason to continue with the case if the tenant has left? - I'm thinking that the court would assign costs to the tenant.

If the cost is assigned to the tenant, does this automatically make the guarantor liable to it (RLA guarantor agreement).

For those rushing in to say I have little chance of getting money from the tenant... I am confident that the guarantor will come good on this.

Jon