All three of these are missing from Core. Firstly:
Doctor Who Mighty Midget #1 (free with issue #1292 of TV Comic, published by Polystyle on 18th September 1976). (The cover blurb saying #1 refers to a revamp of TV Comic.) Artist: John Canning.
Secondly:
Doctor Who Time Lord Victorious Monstrous Beauty #1 (free with issue #556 of Doctor Who Magazine, published by Panini on 17th September 2020). Writer: Scott Gray. Artist: John Ross.
Thirdly:
Doctor Who and the Star Beast #1 (free with issue #598 of Doctor Who Magazine, published by Panini in December 2023). Writer: Pat Mills and John Wagner. Artist: Dave Gibbons.