The entry in Core entitled ‘Captain Britain’ and containing #2: A Hero Reborn; #3: The Lion and the Spider and #5: End Game, is just about correct. (There’s a typo on ‘an the Spider’ and the entry should be called ‘Captain Britain TP (UK)’ or something similar.)
The separate entries ‘Captain Britain: The Birth of a Legend’ and ‘Captain Britain: The Siege of Camelot’ can be amalgamated with the first entry as the missing #1 and #4.
Yes. They’re now listed correctly as a series, but when I then add them all to my collection, #4 gets missed out and appears instead as ‘Empty Series’.