Last time I was out wild camping I woke up and the bottom of my ME down sleeping bag was very wet from condensation from the inside wall of the tent.

Is there some cover I can get for my bag to protect it from the wet?

you can buy pertex (or similar) sleeping bag covers, i know ajungilak used to make one.

like a sleeping bag liner, but for the outside of the bag.

if condensation is a problem, you could try leaving the outer door undone a little bit to improve airflow through the tent, which should reduce the buildup of condensation.

My cheapskate option is to pull a gore-tex jacket over the bottom of the sleeping bag (with the jacket zip done up). Keeps my feet warm and favours the use of a 3/4 length thermarest. Extends a summer bag into autumn use too.

Just get on Ebay, buy an army goretex bivi bag and shove your sleeping bag in it. I always do it, even though my tent produces no condensation problems, it also gives an extra feel of security. I got mine for £20.

The other option is to get a tent with better ventilation. Decent goretex bivi bags are expensive and due to quality and not too long life are not things that should be bought 2nd hand unless you know exactly for how long and for what the bag has been used. Also the problem of the goretex bivi bag is that in very hot weather or temperatures some condensation will build up and the increased heat of the bivi bag will make you sweat more which will bet your sleeping bag wet.

i use a gortex overbag, proved pretty use full this weekend when i had to abandon my tent due to high winds and over exposure to UV degrading the single skin tent i HAD!

otherwise...use any time u can to air the bag....

decathalon have a pertex bag cover (with a dwr i think) for 20notes. might do the trick.
sc

Got one for £20 from http://www.khyam.co.uk

Thanks anyway chaps.

Using your waterproofs has always worked fine for me, unless (like last w/e) you never get a chance to dry anything out, eventually everything is wet.
Trousers underneath (inside out), and jacket on top. Adds another layer, dries your waterproofs slightly with your body heat and protects against problems with the tent (i.e. if it's not there when you get up, holes from broken poles!!)