They already have Google confused and they are serving up .co.uk pages in the index
I agree with the move for a UK site to have a co.uk domain just make sure you are doing it accress the board, properly forwarding the .com and updating all sitemap.xml files and internal navigation
P.S.
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block your plugins folder in robots.txt
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check webmaster tools for duplicate title tags and make them all unique
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Optimize your title tag you have <title><a class="l" href="http://www.sandtoft.co.uk/resource-centre/photo-gallery/photo-gallery-images/?photoID=634&DSID=12">Sandtoft Roof Tiles - Photo Gallery Images</title>
should be something more like <title><strong>Grey Slate Roof Tiles</strong> | Sandtroft Tile Store</title>
with the description of the tile at the beginning of the tag, not the name of the company, that's your domain name you'll already rank for that.