John, I totally agree with you. I too really wish the UK LOTG comics were included in the Hermes Press hardback release in 2013. Their inclusion along with the Gold Key comics would have made that release really complete. Fortunately, most of the UK LOTG comics are available for free download at libgen.io/
Guide to LOTG in UK comics: JOE 90 TOP SECRET Issue 1 (1969-Jan-18) through issue 34 (1969-Sep-06).
TV21 & JOE 90 Issue 1 (1969-Sep-27) through issue 36 (1970-May-30).
TV21 Issue 37 (1970-Jun-06) through issue 54 (1970-Oct-03).
These UK comics were published weekly and contain 2 pages worth of LOTG in each issue. LOTG appears in colour until issue 31 of TV 21 & JOE 90, then in black and white until the final LOTG story in TV 21 issue 54.
Guide to LOTG in UK annuals: JOE 90 TOP SECRET COMIC ANNUAL (1969) Contains 12 pages worth of LOTG comics. LAND OF THE GIANTS TELEVISION STORY PICTURE BOOK (1969) Contents TBD.
LAND OF THE GIANTS ANNUAL (1970) Contents TBD.
LAND OF THE GIANTS ANNUAL (1971) Contains many pages of LOTG short stories, but the comics are only a reprint of Gold Key's LOTG issue #5.
TV21 ANNUAL 1971 Contains 13 pages worth of LOTG comics.
TV21 ANNUAL 1972 Contains a 4 page LOTG short story. Does not contain any LOTG comics.
Below is the first LOTG appearance, from JOE 90 TOP SECRET #1 (1969-Jan-18).