Yeah, I know exactly how you feel! I'm really having a down day today about it. My parents moved to Canada when I went to uni, so going home involves going out there to see them. While most people think it's amazing I get to go out there for 4 months, I hated it last year. Both my parents and my brother have made a life for themselves out there, and have friends etc. However, I knew no one, and really felt left out when my friends from home emailed me telling me all the things they were up to together. I also don't know the little things, and although I learnt them (like how to use the money, where to go to get lightbulbs, whatever) it tooks ages. I got a job, but it was really boring and I hated working there. Although I have my English driving licence, my parents don't trust me with the car there, so I was pretty much stuck at home all summer. Having moved out into student houses in my second year, I feel even more at home here. I've also recently started seeing someone too, and I'm really going to miss everyone so much!
I did try to apply for placements this year in Cardiff, but they've fallen through, and it's looking like I'm heading back to Canada again for the summer. I also think I did quite badly in 2 exams, so might be facing having to fly back for resits. Because of this my parents have decided not to take me on holiday with them, in case I'm not around to go. So I'm really feeling like I have nothing to look forward to (except my 3rd year at uni!).
I know once I get there and get on with it, and really make an effort to do things and have a good summer it won't be so bad, but at the mo I'm just really dreading it. So don't feel like you're alone- once you get that taste of freedom and have a chance to make a life of your own it's difficult to go back!