As a new seller payouts from sales can be held up to 21 days, eBay wish to see that the item has been delivered to the buyer.
Tracking of course is the best evidence of this, but you have feedback confirming delivery.
Not a lot seems to happen over weekends and Bank Holidays so if by Wednesday say, the money is not released contact eBay Customer Services, explain the RM postage was not scanned but buyer is happy with the delivery of the item, they may release the payout sooner.
To Contact Customer Services it's a Live Chat, or you can select to speak and request a Call Back. Click on this link:
https://www.ebay.co.uk/help/eua?id=5275&mkevt=1&mkpid
On the left sidebar you can see Have us Call you or Chat with Our Automated Assistant.
On weekdays lines open between 8 a.m. and 10 .m.
On weekends they open between 9 a.m. and 6 p.m.