Best phone plan for study abroad in Scotland and short trips to Western/Northern Europe

Hello! I will be landing in London in early January, traveling around England for a bit, and then heading to Scotland for 5 months. During that time I will frequently travel to England, France, the Netherlands, and Sweden. Is there a single policy/provider that I can use to be able to seemlessly send texts back to the US and make phone calls to the US as well as texting/calling people in Scotland? I know this might be expensive, but I really need it for work.

Any ideas are appreciated!