Alexandra Friend I’ve got one of these too, they’re ace https://www.selfridges.com/GB/en/product/beast-health-blender-+-hydration-system-drink-set_R04056819/?gclsrc=aw.ds&gad_source=1&gbraid=0AAAAADr4D5j_See1OcYje6hFsEHmopzTb&gclid=Cj0KCQiA8fW9BhC8ARIsACwHqYqmVhf2AjD3Jjpw5l532HHeOZ2c0Ok6ev81GMl-ynIa90JnD_I6ELIaAtrIEALw_wcB xx

I have these https://black-blum.com/collections/vacuum-flasks super easy, plenty of variety on their site too!