I think there’s some fab suggestions here; I’d also add, be kind to yourself - it’s a three hour journey (which can be exhausting with a tiny one), build in some breaks, etc to your journey, so you don’t get an over tired, fractious, hungry baby. Can you eat outside when you’re there? Might help with the anxiety about food-dropping?
Also, as a first trip to see them, your parents might be emotionally completely overboiled, which for some people just comes across as stressed/critical/etc. Cut them (& you) a bit of extra slack with that in mind. It’s hard to work out new roles (like being a GP) at a bit of a distance in normal times, but extra stressful atm. Hopefully that will settle with time.
Finally, although is sounds bonkers, there is a pleasure to be had in listening and sharing the journey that your mum had in looking after you. I found it hard to know quite how to honour my mum’s experience (she was also a bit challenging), except to listen and recognise that she made the decisions she made for me as a baby from a 1970s perspective; but actually suffused with the same love I had for my new baby - and that she shared for him now. I didn’t need to fight her on it; what I did (BLW, b/feeding and the odd top up with a bit of spoonable stuff) was up to me & baby; she had no power in those decisions and lived 200miles away so couldn’t actually do anything about it anyway. For me, realising she did the best she could when she was a new mum, too & was trying to impart her wisdom was really helpful for dealing with what could have been perceived as criticisms.
My grandmothers views were a whole different ballgame however!!!
Sorry if the last bit sounds a bit wacky. Wisdom of elders, you’ll miss them when they’re gone, etc, etc...☺️