Is it possible to retrieve emails that I deleted in Feb as I didn't think I needed them but in hind sight should have kept them ?
Sorry, but no - it's not possible - after 30 days, it's gone.
Quoting from here:
Notes about deleted emails
- If you delete an email, it stays in your Trash for 30 days. After 30 days, emails are permanently deleted from the trash.
- There's only one copy of every Gmail email. If you deleted an email from one place, like a label or a device, it is deleted from Gmail entirely.
- Gmail groups all replies to an original email together in a single conversation. When you click or tap delete, the entire conversation is deleted, including the original email and any replies.
The first point it the one who's relevant for you, but I kept the other two for general knowledge and for the next time an email is deleted.