Kindle on ipad can read aloud any book.
I also used the library to get audio books for my children when they were young.
Regarding books, you will need to pick very carefully if you want them to be decodable at reception level, but enjoyable at Yr 3 level. Picture books like Mick Inkpen’s are on compilation audio book.
Crossbow education have some excellent hi-lo (high interest low reading age) books but these are not audiobooks. You could record yourself reading them, though!