@AngelaW_3071684 As Bulgaria is part of the EU, you should be able to use calls, texts and up to 12Gb of your plan data.
You may need to turn your phone to manual network search if it will not pick up a good network signal on automatic search.
Depending upon where you are going, be aware that your phone may pick up signal from non EU countries; in that case your calls, texts and data would all be charged from any credit you have on your account (no credit, no activity).
I would advise a read of the Price Guide.
Also, you should change the APN on your device to mob.asm.net - details here: https://help.smarty.co.uk/en/articles/2045756-setting-up-your-phone-to-work-abroad
