I would recommend a military sleep system.
it is a series of bags that go inside one another depending on how cold it is.
use the inner bag for summer and fall; use 2 bags for winter.
the USA uses them; I would be surprised if the UK or Swedish military didn't use the same kind of system.
http://www.ebay.com/itm/VGC-USMC-US...738?pt=LH_DefaultDomain_0&hash=item2c7b63c78a
it is a series of bags that go inside one another depending on how cold it is.
use the inner bag for summer and fall; use 2 bags for winter.
the USA uses them; I would be surprised if the UK or Swedish military didn't use the same kind of system.
http://www.ebay.com/itm/VGC-USMC-US...738?pt=LH_DefaultDomain_0&hash=item2c7b63c78a