My first idea was to buy a chaise and strip off the upholstery and use the frame as a basis, this unfortunately wasn't viable for a couple of reasons.
1. A shop bought chaise probably wouldn't be strong enough and the structure was unlikely to be weatherproof
2. Stripping off the upholstery takes ages (see my post about la-z-boys)
3. This is probably the most important - I couldn't find one at a reasonable price
So best I build one myself! I mean how hard can it be right?