Inconsistent date format

Hi everyone,

I have a date column but some have the dd/mm/yyyy in UK format separated by / and others have mm-dd-yyyy in US format separated by a -.

I've tried text to columns ensuring it's date DMY but that does nothing, I've tried converting to text then doing a =datevalue which just errors, =value doesn't work either on the US entries.

(btw I'm in the UK)

I think I'm going to need a column next to the date column which has a formula to make the dates all the same, but my tiny little mind doesn't know how.

Can someone please save me?

Attached is my date column of doom.

Jem