Those Commemorative Coins you have hanging about You know they are Legal tender but Nowhere accepts them right? Wrong! If your not prepared to have them hanging about for ages (Like me who has about 15 1977 Jubilee ones) Here is the guide. Any pre 1990 are worth 25p each After 1990 they are £5 each. You can Spend these for goods or services at any post office. If the post office don't accept get them to do an Internal phone call quoting NBSC. and they should accept as Legal tender.
The alternative is you can list and try and get more for them (All I can say to that is good luck.)