Slovakia without parents

The title says it all but I might as well explain anyway. I have this Slovakian/Vietnamese friend who has lived in this country for about three years now, and for most of his life he lived in Slovakia. So basically, he's quite 'well off' and this is why he's been able to live in so many different places. Anyway, he's going back to Slovakia this Summer and I've been invited to go with him for a week (this is after completing the last of my GCSEs) and I've asked my mum, and she's fine with it (obviously as long as she can see proof of where we're going). I basically just need to know from people anything I should be aware of about Slovakia although I think it's relatively safe. The price I'm paying for the plane is looking to be around £100-£150 from Birmingham to Bratislava return and I'll be taking somewhere in the region of £200 spending money (hotels aren't much of a problem as we can stop at his mother's house for most of the time) and there may be other people coming with us. If anyone finds it important, I'll be 16, nearly 17 at the time. Thanks for any help in advance.