Hi Folks - I'm about to tackle the coast to coast next week with a friend of mine. We are trying to travel light and I've just bought a Belgian Army Mk 2 Bivy Bag (seyntex version 1988 (I think the label says). I'm taking a DD tarp as well with a solo sheet for nights when I think it will rain hard, I'm also going to give it a spray with some waterproof spray. My question is 'has anyone actually used this bivy bag?' - i'm not planning on lying in snow or streams, but I don't want to wake up soaked (from inside or out). Is it any good or have I bought a large sock?