I just realised that apart from my H1b expiration a few months from today, the I94 stamped on my entry to the US is valid for nearly 5 months after my H1B expires, can I still work to that date then renew the visa?

What is the validity date on your I-797 approval notice? Does that correspond to the date on your I-94? If so, that is the expiration date of your H-1B employment authorization.