When u get any ordinary coin or bank note always check it on ebay, have a look now at your change now!
Just a few days or so ago i sold a 50p for just over £3.50 due to it being a certain design (which is common as hell around here), please let me know if you also manage to sell anything strange or if any of your cash turns out to be more than you thought. Also look up the note serial numbers to.