A few possibilities (which may not be right either - it's many many years since English Alevel):
1. The fate of both is driven by external supernatural force - Macbeth by the witches' prophecies, Tess by Fate ("As flies to wanton boys are we to the gods..." quote from King Lear if I remember rightly)
2. Both are driven by others to take on roles above their present station - Macbeth is encouraged by his wife to become King of Scotland, Tess is encouraged by her father to claim their birthright as D'Urbervilles
3. Both think they've got away with it - Macbeth feels safe after being told "none of woman born" and Tess mistakenly thinks she can confess to Angel Clare.
Don't know how much that helps, and may be barking up the wrong tree altogether.