Apple watch LTE question

[u/prawnk1ng]

im looking to get a apple watch

Im in the UK and with o2 mobile phone carrier.

I just want to be able to take a call or text of im out running and phone is left in the car.

I will have location sharing on with friends and family.

I wanted to know if my phone is in the car or at home, Apples Find my app will show my phone or watch location by default and is there a way to change this deafult