So, if she can do a Cockney accent - like she did in BILT
That is NOT a Cockney accent in BILB. The Cockney accent is from East London, Archie and her charcter from BILB is from West London - Hounslow to be more specific.
If you want to hear a cockney accent see Michael Caine's 60's films - Alfie, The Italian Job. But Archie's accent in BILB is a typical working-class West London accent, which is where she's from anyway.
She's an actress, she can do many accents. She does an Indian accent in A Good Year.

"England really?? she looks Indian"
Seriously?? Have you not heard of immigration? She's British Asian (like myself) with ancestry from India. Like me she also happens to be from London.
And Panjabi is an Indian surname.

can't you read?
Old lady wheelchair chicken challenge!