Scared of my dad?! help please?

Ok so I'm meant to be seeing my dad for one week by myself I've asked if I can take a friend down to wales (where he lives) and he's turned round and said no...I'm scared of going down on my own, he drinks every night and can get very nasty and violent, normally I have my sister but she wont go this time...I still want to go...I need to see my 2 year old brother and leah and I do want to make things work with my dad...just I actually feel sick because of this fear, and I already get anxiety attacks, I don't know what to do...if I had one down there he would probably call me mental...again...just really scared but I know I need to go...help plz....and he wont let me call any friends or email them...he never does... :\ plz help, what do I do?