[The Squatter of Amon Rûdh]

A thorough reading of the Lost Tales ought to furnish their themes, not to mention a good read all in the name of work. By and large they detail the earliest conception of the myths that became the Silmarillion, at this initial stage still intended as a new mythology for England. Some of the descriptions are the most complete that Tolkien ever gave, as with the account of the fall of Gondolin. Each tale has its own theme, as with any mythology, so it's difficult to give a short explanation of what it's all about, but an examination of the key legends would probably be the best approach for a short report, perhaps with a brief examination of the issue of Eriol. This material could be tied in to the poem Kortirion in the Trees to furnish an interesting discussion of the way in which the original conception of the Tales sets up the two main British islands (the current United Kingdom and Ireland) to be two halves of Tol Eressëa, so that certain English towns, such as Warwick, become locations within the legends. The association of the stories in the Lost Tales with England specifically and explicitly is at the very heart of Tolkien's original ambition for his legends, and it's interesting that this theme was abandoned in later writings.

I hope that helps a little.