Yeah, don't ever do that again! Work email is not for personal stuff.
Here's what you should do. Get yourself a free personal email address with Gmail or similar.
Make a list of your financial and health accounts first and before you leave get all of them changed over to your personal email. Banks, credit cards, mortgage, HMRC, loans, hire purchase or lease car, plus NHS and your GP practice log in.
Then do utilities: energy, TV, broadband, water, mobile phone, council tax, TV licence etc
Then do insurance: car, breakdown, home, travel.
Then start trawling through your emails for all other personal emails from organisations. Forward 1 from each to your personal email. Include any from the above sections that you don't manage to get to before you leave the job
Also trawl your bank and card statements and PayPal for money you've spent recently. You'll remember spending online, so you can contact those. I'm thinking Next, Shein, M&s etc
And just to repeat, don't do it again 😁