I did a Europe trip (Czech, Germany, France, Holland and UK) and a disposable didn't touch Gracie's bum
Honestly you can easily do it especially staying with MIL!
But laundrettes/laundromats are always a good option too if you don't have access to a washing machine for some reason
We used a mix of fitteds, flats and quickdry AIO while over there
You will have a ball!!
Bec.