First time abroad. Have I got everything?

[WillTheRealDeanGaffneyPleaseStandUp]

As above. First time abroad.
Me and my 15yr old. Travelling by Eurostar and local trains to s few countries.

I have -
Passports!
Proper insurance
ECHI card
I've worked out what bank card to use
I've got some euros
Travel is sorted
Accommodation is sorted
I've prebooked some of the popular/must do activities
I'm as sure as I can be that my phone will work.

I'm quite nervous. Have I forgotten anything obvious?

Love a Eurostar trip!
As already said, travel adapter is a must but instead of bringing multiple if you get one (or one each) of these universal adapters with multiple usb ports you can all your devices in one go, so much easier!
Also, nail clippers are so unexpectedly essential, easy access toiletry bag for travel days, foldable water bottle

www.tribefeel.com/products/best-usb-c-travel-adapter-uk

Sounds fantastic, you will have a lovely time, and your list is great
Download Uber AND Bolt if you have not already
Get an e-sim if you have not got roaming, and get one for your DC too (they are a couple of quid, make sure you have the right phones (unless it is a really old phone, it will be fine) follow their instructions (it is easy)
Whatever bookings etc. you have, just forward to your DC email also, as a bit of "contingency" if your phone is out of action.
Small fast charge power bank 10,000 mah should do most jobs
Get Deet (roll on is better than spray imo - it just chokes you and doesn't cover your skin the same) and you can save a lot of bother by just wearing longer sleeves and trousers at night. We use Jungle formula max strength for the exposed bits. You can get bitten in the day but it is unusual. If you have any choice of room/ balcony, higher is better. Mosquitos prefer to fly under 25 feet.
You are completely right to get a money belt, I wear mine under clothing.
Everyone does their payments different, but I take one reliable (no charge card, and really like Monzo, have also done Halifax Clarity card, and Currensea) Then a back up card. (DC may also take one, even if yours, just because when you access public transport, you need two cards). Only take money out in "proper" ATMS not the street corner ones.
If either of your phones does Google Lens, it is a life saver in restaurants (or in fact anywhere where foreign signs are) because it instantly translates them, it has probably saved me from ordering randomly and getting sheep's testicles or something....there is probably an iphone equivalent.
If you have washing machine anywhere, take washing sheets from the Green Company" (I am not affiliated in anyway, have just found them an absolute godsend when doing ultra-light travel) These small sheets of what looks like thick paper have done a half load admirably in AirBNBs

Finally, travel light. Half your stuff, then half it again. You can buy stuff if you REALLY need it.

Sorry, I have gone on forever here, but I hope it does help xx

Ziplock bags and clips to put food in. Cheap to buy things like baguettes, ham, butter for journeys, take bits and pieces from breakfast if you get breakfasts.
Anything you want yo watch downloaded. Though french trains at least give you films and wifi!

If youre interrailing, recommend printing your tickets and putting in a folder, not essential but if you dont have charge on your mobile you could be stuck. Lots of trains in Europe you need to book a seat in advance and can't travel without a seat. I say lots of trains, mainly france, worth double checking.

You'll need an adapter plug for Europe to charge your phone.
A power pack
I always take a first Aid bag with plasters scissors etc than add in diarrhea tablets, headache tablets and wet wipes.
A waterproof bag for phone
A couple of bottles of water

Phone number and ref number of your travel insurance.