UCL econ chances? (2026 entry)

my dream is to go UCL for econ and im sitting the tmua on the 13th of october but icl im finding it hard during practice and im worried that i might get a bad score. im applying early for cambridge, lse, ucl, durham and bath. i currently take math, further maths, econ, physics (a*a*a*a*) + econ epq (a*) and my ps is decent. but a big issue is my GCSEs because until year 12 i never wanted to go uni in the uk so i sort of ****ed around and got a few shocking grades (still secured math a*). how important is the tmua for ucl econ and what are the chances i get in??