for the main image size, edit the width property of the following selectors ion the common.css file:
.pg-rfl
.pg-rfl .fullsize
.pg-rfl .title
.pg-rfl .nav
the mysql error does not show if i access the gallery directly:
ribbon_fullsize_lightbox_island_view_custom/
this leads me to thing it is caused by something on the holiday-home-to-rent-in-looe-2.php page, send a copy of that page i a zip archive so I can take a look at the code.