Hi Ginger66
You do not need to send your P45 to HMRC as your old employer should have done so.
When we received notification of your employment ending, a tax code change should have been prompted.
If you wish to check your current tax code, you can do so using the online service here:
Check your Income Tax for the current year
Alternatively, you can contact HMRC here:
Income Tax: general enquiries
Thank you.