so the real problem is that you are getting the headers already sent error, looking at your page, it looks like the gallery is there, just not displaying because of the error.
the error message is reporting the output at line 1:
output started at /home/users/uks66722/html/206bones.co.uk/store/Products_Detail.php:1
this usually happens if the page has been set to Include Unicode Signature (BOM). Go to File -> Save As. In the Save As Dialogue box, uncheck the Include Unicode Signature (BOM) option.
if you still have a problem, please send a copy of your Products_Detail.php page.