I've just started reading The Hobbit again, the last I read of Tolkein was LOTR. Does anyone else find his writing style, comparing the Hobbit to the LOTR, to be completely different?

I think I heard somewhere that somebody (Tolkien?) said LotR was a children's story got out of hand.

Yep.

Tolkien started the sequel as a children's story, like the Hobbit.

However, the primary audience that he wrote for remained his children, and they had grown up. Consequently (though only partially because of this), the story grew too,

and he later had to go back and revise his earlier stuff so that it would be more in-line with the older-essence that the Lord of the Rings had gained.

Really? I sort of remember that he wanted to write the story of the end of the Third Age, and then he thought of connecting it to The Hobbit.

(Not that I care enough one way or the other to go digging in the relevant volumes of The History of Middle-Earth, the Christopher Tolkien-edited critical editions of all of his father's old drafts and revisions. )

I agree that the primary audience was always his children, who had indeed grown up, but in the introduction or preface to The Lord of the Rings he says that he had the whole story in mind from the beginning.

The only major-even-for-Tolkien revision-for-consistency that I'm aware of is that after The Lord of the Rings was published The Hobbit was revised to make the sequence in which Bilbo acquires the Ring fit how The Lord of the Rings said it happened.

I liked Roverandom, Letters from Father Christmas, and...the one where there was a magic silver star in a piece of cake? Anybody know that one?

That would be Smith of Wooten Major.