I have a Blue Bird Hammock fitted in the front of my Westy.
http://www.bluebird-type2.co.uk/
* interior part, quarter way dwon page*
However they advise you to fix it to the A and B frames and that it will fit.....It does in a Bay but not in a T25.
My daughter sleeps in the hammock and says it really comfy, she's 5 now but had she have been a baby I would still have put her up there. We devised a curtain to go across the front seats so she could go to sleep in her own little cocoon.
Others have bought them from JK as cate said and I think they are a better fit for a T25.
Personally, I am thinking of adapting mine so it will fit just below the windows, means getting the sewing machine out but is all good experience.
Lots of others have bought and home made ones in their vans, if you need pics, pm me and I'll send some off to you.