I will take (polite) issue with peteneras.
UKCAT is one of several hurdles that prospective medical students are expected to jump. Different medical schools have different requirements. Medicine offers a variety of careers involving different skills.
For my bright dyslexic daughter, UKCAT was by far the highest hurdle. Even if she had practiced from Christmas on, she would have struggled with the speed requirements. And extra time does not help when everyone expects to be brain dead at the end of normal time.
Oddly her dyslexia comes with complementary skills. She learns by listening, has an extraordinary memory and picks up concepts quickly. She is also very practical. She will be far more suited to a busy A&E than a branch of research medicine. Whilst the boy we knew was putting in hours upon hours in his bedroom practising for the test, DD was on the sports field, or volunteering with a local disabled group. (Or watching US medical dramas, which had an unplanned advantage of contributing to her wide medical general knowledge.)
She got the A level grades with a good margin, she is fine with the academic and non academic aspects of her course. She just happens to be useless at timed aptitude tests like UKCAT, CAT and 11+.
The advice still stands. Practice helps, and you want as good a score as possible. For example if DD had not, effectively, given up, her strong GCSEs and a slightly better UKCAT would have put her in the running for Nottingham or Cardiff. She was lucky because at the time Bristol did not use UKCAT. There is no way she would get a place there now.