As you are starting so early, it might be best to ask a HV as they are trained in this kind of thing and don't normally recommend weaning before 17 weeks but from 17 weeks I think you can start including fruits and vegetables. The kind of ones we started on were:
Pureed; parsnip, sweet potato, swede, carrot, butternut squash, apple, pear. Just watch out as loads of them are orange, it can send their skin orange if they have too much!