Beth. Please do not worry. One of my girlfriends came over last month for a week from the UK. She got through no problem (though I questioned that when I saw how she was dressed!!!!) she also stayed at our home. She did not have our address on her but immigration was fine. If staying with friends just take a note of their address and have thir local number at hand so that you can call them if you get stuck. Seriously, you will have no issues. If it makes you feel any better, I can always give you my friends number in the Uk and she can talk you through what happens at immigration.