No idea whether this will work! But if you are able to download bank statements from the Co-op in .qif format (Microsoft money) then have a go by using “Santander qif file” that is an option in QF bank statement imports.
I recently posted about how the Santander qif file format is useful when working with French comma separated files “La France sur virgule dans comptes bancaires” but afterwards mistakenly imported the file into an HSBC current account and that also worked (had to do a “Recent Batch Uploads deletion” to fix my upload error but that’s not too problematic).
Have a go @madbilly and as I suggest if you make mistake there is also the facility to fix such import errors.