DO NOT ever ship anything until the payment has cleared, NOT Pending. Otherwise they will reverse the payment as soon as you send it. Go to Paypal.com and if there is no money in the account you don't send anytning

Also Paypal PROHIBITS all transactions with Nigeria due to fraud so you cannot send anything to Nigeria. You have no protection from Paypal if you ship to Nigeria. You ONLY ever ship to Paypal verified addresses which cannot be in Nigeria

You would also never send anything of value like a laptop through Royal Mail as postal theft is a massive problem in Nigeria and it will get stolen. The only safe way is through a private courier like UPS, DHL, TNT, etc which is going to cost you easily £75+ plus you need insurance.

I work for a company whose African head office is in Nigeria and we don't send anything through Royal Mail anymore as things never arrived and got stolen. We sent a package with 2 empty sample bottles and even that got stolen - the thieves dont' know or care what's in the packages. They just see a package from overseas and steal it

Before you do anything CALL Paypal and get the verified address of that Paypal account, then write to the buyer and tell them that per Paypal's terms you are not allowed to ship to Nigeria and will only ship to the verified address and it's THEIR responsibility to ship it to Nigeria