We used Wilma's Nordic Summer Midgie Repellent last year and it seemed to work quite well. It's quite expensive but it lasts a long time. This is the first seller that came up when I googled it but there are probably others, maybe cheaper:
http://www.woodland-ways.co.uk/buy-online-wilmas-nordic-summer-insect-repellent-113.html
Smells nice too! And you don't look quite as slimy as when you use Skin So Soft!