The cover image originally adorned the cover of Marvel's Planet of the Apes #11.
The contents are as follows:
[Terror on the Planet of the Apes] Evolution's Nightmare!, originally published in Planet of the Apes #5, February 1975
A Visit with The Fantastic Four, originally published in Fantastic Four #11, February 1963
The Hulk vs. The Thing, originally published in Fantastic Four #25, April 1964
The Avengers Take Over!, originally published in Fantastic Four #26, May 1964
There is an odd edit in Evolution's Nightmare. This is page 3:
This is page 4:
The black text caption at the beginning of page 4 reads "and the view from the other." In Marvel's Planet of the Apes #11, this caption appears on the preceding page, at the end of the panel with the speech balloon "...but it's human cunning that'll win this day." The edit was presumably compensating for the cropping at the bottom of page 3.
The listing of the contents above suggests that three Fantastic Four features were reprinted in this issue. This is not the case. Only the splash page to A Visit with The Fantastic Four is included from Fantastic Four #11. It is printed before the beginning of The Hulk vs. the Thing. The splash page for The Hulk vs. The Thing is not included. In effect, Newton have presented The Hulk vs. The Thing as beginning with the splash page to A Visit with The Fantastic Four. I'm not making this up:
Newton rectified this butchery later in their Team-Up Special in which they reprinted The Hulk vs. The Thing and restored the original splash page.
On the face of it it's quite bizarre for a Planet of the Apes Annual to predominantly carry Fantastic Four material. On reflection, my guess is that Newton rather cannily selected these Fantastic Four stories in particular in order to showcase not only The Fantastic Four but also The Hulk and The Avengers in an effort at cross promotion by piggybacking onto the success of the Planet of the Apes series, which had been the beneficiary of high profile promotional efforts. All three properties were advertised on the cover of the Planet of the Apes Annual, and I don't think they were indiscriminate padding. It may even justify the inclusion of the single page from A Visit with The Fantastic Four given the page promotes Fantastic Four comics.
The Evolutions Nightmare! chapter of the ongoing Terror on the Planet of the Apes serial, published in this issue, is set between Planet of the Apes #4 and Planet of the Apes #5. On this basis it would make sense for the Annual to have been published in between these two issues. The contest in this issue expires 15 September 1975. The expiry date for the contest in Planet of the Apes #4 was 8 September 1975 - one week earlier. The expiry date for the contest in Planet of the Apes #5 is 22 September 1975 - one week later. This settles it for me - these three issues were published over three consecutive weeks. And if Planet of the Apes #4 was indeed published 19 July 1975, as I suspect, then this Annual was published a week later on 26 July 1975.
The Annual was advertised a week later in Planet of the Apes #5: