Use lip balm, my lips were ruined, cracked and very sore.
Don’t get suntan cream with a pump bottle, mine and one other failed. Use a tube!
Take a solar panel and battery (if you have one). Easier than recharging at a teahouse (it’s just a faff).
Take advice on what and where to eat, the guides have a good idea what each place does well.
Don’t worry too much about the food, yak steaks, fried eggs and chips are lovely!
Pack your gear in waterproof bags, it can rain and the porters might not cover the bags!
If you can walk up Scarfell Pike or Snowden, then you can handle the terrain. Altitude is an unknown till you get there.
If you camp at EBC you need warmer clothes and sleeping bag!
In the teahouses my sleeping bag (-9 comfort) was too hot and used as a quilt. At EBC it was just warm enough. (For me at this time of year).
Walking shoes were fine.