Hey Goncalo,
Im going to Ph3 on the 2nd aswell.
If you think you are going to have trouble with your english in "pressure" situations the only way to get over it is practice!
Give some sort of brief to as many friends, relatives and randomers that you can scrape together. I had a similar problem a while ago and practice has helped no end!
Good luck and I'll see you in April!
Cas