The tracking number will be on your post office receipt. Even if you didn't pay for tracking there will be a 16 digit delivery confirmation number on there which ebay accepts as tracking.
See if you can add the number to the order by going to the Order Details > Postage > dropdown menu (beside track package) > Add Tracking > + Additional Tracking Number.
If not contact ebay and ask them to do it. You can use callback on here:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
Without tracking the money will be released anyway after 14 days so you will get it in the end.
@6970karen