A 4 in Physics 1 for CompSci is not a good sign. IF you got an offer it would be conditional on 5s in (my guess) Calc & the 2 Physics. Odds of an offer are, obviously, rather better at UCL than Imperial.
I am guessing that you were very confident about 5s for this year: realistically, why will next year (when you have 7 to prep for, not 2) be different?