What I do in similar situations (i.e. going to Europe) is go to an actual physical brick-and-mortar cell phone shop (such as a Vodafone shop) on the first day of my trip and buy a physical SIM card + calling plan, and don't bother with trying to get an eSIM ahead of time -- because with an actual SIM card, you get full service at a low price. For example, Vodafone has these "£10 Big Value Bundles" that'll get you all the data you could ever need and infinite free calls and texts for an entire month for just £10. And the SIM card is included free with it.
The downsides are that you won't know your number ahead of time until after you show up, and also you won't have cell phone connectivity when you get off the plane, until you visit the shop and get the physical SIM card. That's why I always make "go to cell phone shop and get a SIM card+plan" be the very first thing I do upon arrival in Europe.
There are other companies too with other plans, and sometimes even shops in the airport -- but the airport shops are generally way overpriced. So research the shop nearest the transit exit from which you'll be debarking, or the shop nearest the pace where you'll be staying, and go there as soon as you arrive.
With some companies, you can even keep the SIM card and re-use it on your next trip up to a year or more later, but sometimes the SIM cards expire and you need to buy a new one.
