Peach Tree Leaf Curl Problem
I would recommend VitaxBordeaux Mix. This is a copper based treatment that is suitable for Peach Leaf Curl.
In order to prevent the disease occurring in the first place, it is a good idea to keep the tree covered
between the leaves falling in Autumn until May with a Peach Fruit Tree Proctector. This stops the infection taking hold and offers protection against frost as well.
I hope this is helpful.
Please let me know if I can be of any further help.