Prepaid eSIM for Galaxy Active 2 watch

Could someone describe the the process of getting an eSIM for an LTE Smart Watch. Specifically the Galaxy Active 2. Or just some key pointers to get me on track...

I am currently not a cellular O2 customer (But I do have a Home DLS service via O2) 

I want the smart watch to be able to work ‘stand alone’ without the need to access a Smart Phone handset. But I do have access to a spare Samsung Handset for setup.

I’m looking at one of the Annual Prepaid tariffs with data & Voice….. But first I’m happy to work with a plain monthly prepaid tariff in case I find for some reason I can’t do what I want and then roll over to the Annual Prepaid when all is working. 

I read some where that you order a standard SIM, (Which I have done but waiting on delivery) and then convert it to an eSIM? or do you add an eSIM to this? The Idea of having a standard SIM in a handset with the eSIM working in the watch with the same telephone number could be a benefit? so long as they don’t interfere with each other?

Regards

Oliver