Book evaluation help!

Yes, these are later impressions of the first UK edition.

Usually in book-collecting circles, "first edition" means the first impression, but the term is a bit muddied here as Tolkien changed the text in 1966 and those coming after are known as the "second edition".

So they are the first edition in one sense of the term and not in the other sense of the term. They look to be in relatively nice condition and would be worth a few hundred pounds in the current market.