following up a section 21/accelerated possession order with small claims for rent arrears

Rent Arrears

Hello.
I am seeking accelerated possession of a property from a tenant and am waiting to hear from the court to identify the possession date. The tenant has put in a defence to extend the possession date but we should soon at least have a date.
The tenant is also in growing rent arrears and is not paying rent during this court process.
My question is this: once we have a date for possession, am I then able to pursue the tenant through the small claims court to collect the 4 months' rent arrears?
My concern is that if I leave it until the tenant leaves to pursue the rent arrears, I won't have a forwarding address with which to direct the court documentation.
The issue that I am unsure about is whether the County Court will allow me to pursue the rent arrears, whilst the tenant is under instruction to vacate the property, from a separate court process.
Thanks