Hey there, I am sorry to hear you got rejected by the three medical schools you applied to. Fingers crossed that you will at least get called for an interview at Bristol. The shortlisting process is rather subjective in my opinion, as they have to filter out thousands of applications for only a few hundred interview places. You have excellent extra-curriculars, but I doubt they read every applicant's personal statement. I am a reapplicant this year as I got rejected by all four medical schools last year. Thankfully, now I hold an unconditional offer to study medicine at Cambridge
My advice to you is this. If you decide to reapply this October, make sure to commit more time in preparing for your application. Focus on your weakness. For example, you mentioned that your UKCAT score is low because you're a slow reader. I was a slow reader too. But this time, I came prepared. I learnt how to speed read, almost doubled my words per minute read. My VR section of the UKCAT improved vastly as a result. I don't recommend going to any of the UKCAT courses at all, as the key to doing well in my opinion is practice. Plenty of cheaper and better alternatives are available, such as investing on a Medify subscription.
Be mentally prepared to go through what you went through all over again - the admissions test, personal statement, waiting for interviews, interviews, and more waiting again. I also suggest organising some mock interviews for practice as you did not manage to get any interview experience.
My choices last year were quite ambitious, but this year my uni choices are more conservative. Do your research and always apply to your strength. Your UKCAT this year is slightly below average. Applying to unis that uses the UKCAT as part of their shortlisting process isn't such a good idea. Unis like Cardiff only uses the UKCAT in borderline situations, while using personal statement and academic results to shortlist applicants for interviews. Also, a bad UKCAT isn't the end. You can always try applying to a BMAT university.
The best thing about reapplying is that you could actually buckle down and prepare yourself for the admission tests and interviews, since you have completed your A-levels. Take the year out to do some postive things, like learning a new skill, or volunteering. I'd be happy to answer any of your questions through PM if you want!
Good luck