since queen Elizabeth the 2nd is the commander of the army in theory could she overthrow parliament and take absolute power?

No, not according to the constitution. The Queen acts on the 'advice of her ministers'. Parliament is sovereign.

NOT legally

She could try

but she doesn't want their debts

She's 97 years old

unlike your twisted president who can do that , the head of the country is the PM and to that would be an uproar in parliament

The British queen requires the permission of parliament to order more than the changing of the guard.

Of course. That makes hella sense.

She can dissolve Parliment if she wished, no need for the Army

Historically this hasn't gone well for British Monachs in the past, Google the British Civil War

Supposing she could, why would she want to? She has a pretty swell life right now. All she has to do is observe proper protocol and etiquette and everything she needs is provided for her. Why would she want to rock the boat and try to actually run anything?

I think she would need a nap first.