I suspect that this is not cardiac related and it is incidental. But with your symptom of dizziness and bradycardia and your GP's concern followup is prudent and not a waste of time. "urgent" and "three months" don't seem to belong together.You certainly have symptomatic gastrointestinal disease, diagnosed IBS but some of the symptoms sounds like gastroparesis. I would continue to followup with gastroenterology for workup and treatment.
I have zero other health issue than those noted in my post, when I was very young I had migraines and I have always had dodgy joints (again Im getting older and runs in the family) and that is about it.I have never had any ailments you noted. When first diagnosed with IBS I was given lansoprazole in case I had an ulcer. But generally I have been in good health most of my life and taken little medication. Its just a bit cloudy all at once now I have reached my mid 30s  Blood tests historically are fine only regular things to note: I consistently have high bilirubin in liver blood tests but as the rest are fine this is usually noted as Gilberts syndrome? And again, not an issue. Cholesterol is teetering on high side but still currently in normal range. High but normal MCV in last few blood tests (~100)Im more concerned that I am not in need of an urgent referral and wasting time? But secondarily would like to know why I feel so rotten, and if it could relate to heart at all? It would be great if I could actually see the results and notes - I should call and ask for them and see if they will share!