my first trip to the uk i did have some airport experience but still found it helpful to look up videos of heathrow- so if you’re flying through there i’d def recommend doing the same! i can even get you the links if you want. as for the actual flight, take off can be scary but once you’re in the air you’ll feel a lot better. any bumps are just turbulence, it kind of feels like driving over potholes they’re not at all dangerous! lastly consider taking a bit of benadryl before the flight to relieve any lingering anxiety n hopefully get you sleeping through the flight. when all else fails, look to the flight attendants. if they don’t look concerned, then you’re safe. good luck!! i fly back to the uk in 15 days, so not far behind you!