Contextual Offers - LSE, UCL, Bristol

just had a couple questions about contextual offers.

A-levels: A*ab
gcses: 999998877

1. Can gap year students also apply if they are eligible for the offers, or is it just current y13s?
2. If i'm on a gap year, my predicted grades are irrelevant now and the focus is on the grades i've already achieved? So i already have a grade below the entry requirement.
3. I did psych, bio and chem for a-level, but am now looking at courses like politics and international relations. Would i be able to compete with those who've studied a-level politics, economics, maths etc?
4. Do i have a shot at applying to top unis like lse, ucl as their contextual offers are aab/abb if i write a good enough personal statement?