Tenant moved out but not letting me enter

Possession - Section 8 and Section 21

Hi Everyone
I've had a tenant in my property for over a year and housing pymnt came directly to me until last week,i rang my tenant to see what was going on and she never replied after a few txts and phone calls over a few days and no reply I rang housing to see what was going on, they told me my tenant has another tenancy agreement in place as of 8th aug but has not given any dates to when she has moved out of mine and into new house.

I went to house and curtains closed through day so I decided to have a look inside,she has left a few odds and sods and a minging quilt cover which absolutely stinks of pea and you can smell it throughout the house,also I haven't a clue what kind of plants she's been growing in the back yard but there about 6ft high.

I txt her to say I know she's gone and the house is disgusting which to that she replied saying she is going to take me to court for invading her privacy as she has not yet handed her notice in.

What steps can I take to enter my property as surely she has to make a decision soon for the benefit of her housing to be paid on her next house.

I really don't want to have to go through the courts as this is unnecessary waste of time and money for the sake of the bitch trying to be funny.

How dare tenants treat landlords like this and the sad thing about it is theres nothing we can do.

With the confirmation that I'm waiting for from housing to confirm her new tenancy date do you think this will be enough