on the product detail page, there is javascript code that is used to display the price of the selected option.
look for the following code:
if (xmlHttp.responseText != "") {
var theRet=xmlHttp.responseText;
var thePriceField = "$"+ getFromRSDump(theRet,"ProductPrice");
if (thePriceField.indexOf(".")==-1) {
the dollar sign is on:
var thePriceField = "$"+ getFromRSDump(theRet,"ProductPrice");
change that to display your pound sign:
var thePriceField = "£"+ getFromRSDump(theRet,"ProductPrice");