I'm currently doing Triple Science, and 90% of my year group also picked triple science, even though they weren't looking for a science based career. If you want a to persue a science based career in the future, it is advisable to pick triple science as it will be a bonus for A Level and will get you more prepared. Target grades and predctions doesn't mean that you will just get your target grade, as people improve a lot in 2 years of their GCSE course and tend to achieve higher than their target grade. At the beginning of Year 7, my target grade for Latin was a Level 5, but by Year 9, I had a Level 8. My advise to you is just be optimistic and pick Triple, and I'll guarantee that you won't regret or in the future. In the meantime, Good Luck on your decision.