Presuming they'll be rising 4 then you have a state preschool as part of Goose Green Primary which is well regarded (I think Bellenden Road Primary has one too, but I know nothing about it). All of the pre-preps have 3+ entries although waiting lists can be long, we had a good experience at Oakfield and friends of ours loved The Villa.
There are regular threads about day nurseries but I don't know anything about them.