calling from england to gibraltar

I am looking at getting 2 simcards. One sim card is for myself & i would like to be able to phone Gibraltar. Which sim will i need and how much?

The second Sim will be for my partner who will be in Gibraltar, he will want to call me in england. WhIch sim would he need? And how much?

Also will we have to pay to receive calls from eachother? And if yes, how much?

Thanks