Thanks for the replies. I knew you chemical-savvy lasses were out there somewhere!!!

Kate08- interesting comment about the 'biodegradable' nappies. Apparently there are strict conditions for them to completely biodegrade- unfortunately I haven't looked into it- but I have thought about doing what you have done- just throwing one out the back garden and seeing how long it takes.
The nature babycare ones at least don't claim to be biodegradable- just chemical free- which is a step in the right direction at least!!
I found cloth hard in the early days when runny breastfed poos were so regular- but now that bub is a 1-poo-a-day-man, its too easy for me not to use them. Bit of wee just comes stright out in the wash!! Although, the eco disposies ARE really good for night time use......