taking possesion early?

Tenancy Types and Management

we have a 6 month tennancy with our current tennants which is due to expire at the end of july. we issued them with the section21 at the start and we are acting on this to end the tennancy. for the past 2 months they have paid the rent in smaller instalments without asking us to do so and are currently £200 in arrears with this months rent. we have also jst found out that on several occasions the police have been called to the property and there has been noise nuicance ie loud music much of the time. we have tried to inspect the property giving them the correct notice to do so and they were not at the property. is there any way we can get them out sooner than the end of the month?