You should call your carrier in the UK and explain that you need to unlock your phone because you are travelling. Unless they're being particularly unhelpful a carrier will normally give you the unlock code for that purpose.

You should call your carrier in the UK and explain that you need to unlock your phone because you are travelling. Unless they're being particularly unhelpful a carrier will normally give you the unlock code for that purpose.

Edit: It looks like the unlock code may be stored on the device and accessible as with many Galaxy phones, most easily if you are rooted. Check out this AndroidForums guide.