Hi JPP,
If your listings are posted on the eBay.co.uk website, the GBP currency symbol should be displayed in your Auctiva store. If the incorrect currency symbol is still displayed next to the eBay UK listings in your Auctiva store, please contact our customer support department using the appropriate link on our help page:
http://www.auctiva.com/free-auction-software-help/help.aspx
-Mike