Congratulations and though your anxiety about it is understandable, don’t worry, it is very doable and will be a lot easier than you think. My son took his first flight (12.5 hours HKG-LHR) when he was 3 months old and is a fairly frequent flyer now. I have travelled with him many times on my own including as a toddler.

I echo the comments about him having his own seat. Also use the opportunity to board before everyone else, that’s what it’s there for.

I always take a bag of activities: books, colouring books, pens, cars, lunch/snacks. I don’t use a tablet/ipad, it is absolutely not necessary unless your kid is accustomed to it which at that age I’m going to assume is not the case. Take a favourite soft toy.

BA staff are generally quite good with young kids. I know exactly what you mean about being self-conscious about noise etc, but even if your kid is crying or whatever endlessly, although people around might be wishing it was quieter, 99% are understanding (many are/were parents too) and only the most unreasonable are going to feel annoyed about it. And if they do it’s their problem. The worst passengers I can remember were all adults. Kids are kids.

Good luck and enjoy your flights.