From wiki:
"Mosquito netting can be made from cotton, polyethylene, polyester, polypropylene, or nylon.[6] A mesh size of 1.2 mm stops mosquitoes, and smaller, such as 0.6 mm, stops other biting insects such as biting midges/no-see-ums."
To be honest in the UK I'm not worried much about desease spread from bugs (apart from lyme disease) but if you do cut netting to size you can fit them to window frames with double sided sticky velcro tape which is cheap enough on ebay.
Another option is
http://www.ebay.co.uk/itm/Mil-Tec-Milita...3641.l6368 shop around and get them cheaper, use them on their own or on a 'cot' bed, we did both in Iraq and Afghanistan and they were needed out there. In the UK they work well under tarps, the sown in groundsheet makes sure your bug free.