Here are some more specific numbers for you UK:
Top 10 Tourist Markets by value for the UK in 2012:
1 – USA
2 – France
3 – Germany
4 – Australia
5 – Irish Republic
6 – Spain
7 – Italy
8 – Netherlands
9 – Canada
10 – Switzerland
Top 10 Tourist Markets by visitor numbers for the UK in 2012:
1 - France
2 - Germany
3 - USA
4 - Irish Republic
5 - Netherlands
6 - Spain
7 - Italy
8 - Poland
9 - Belgium
10 - Australia

GCC might have business investments etc, but their spending as tourists really doesn't amount to much for the UK.