I've had one lock apart and can see no way I can change things internally to change the hand. Its hard because things are held together with a circlip and my circlip removing tool has pins that are too big!
It seems
screwfix may have a latch that fits in which case I will go down that route. If I cant find a replacement latch then I'll try taking one with the correct 'hand' apart and use it as a model to see if I can adapt the problem one .
Thanks for all or suggestions