You already know the answer. Should you be able to make a 12:30 flight? Yes. Probably 90%+ of the time.
Then try listing things that could happen. Ship is late, delay in disembarking, traffic issues en route, delay at passport control or customs (UK not in EU any longer), labor issue, weather.
No idea of your final destination that day, but my general rule of thumb is if I need to ask about having enough time. I don't.