Well I have just phoned the kittens fosterer, she said they are getting big, playing great and are still on mums milk. She said she did try to wean them because they are so big for their age (4WEEKS and 4DAYS) but they were not interested so she is going to have another go next week when they are 5 weeks. I asked her what she will be giving them when she does wean them onto solids, and she said a brand kitten food,only a little, mixed in with cooked chicken and warm water. So that is what they will be eating whilst at their fosterers. So I guess any more advice on introducing it gradually will be a great help.
Thanks for all the info, Emma