UK Stutterers - medication?

UK Stutterers - medication? I've been stuttering since I was 14 (25 now) and while my stuttering has improved with avoiding certain words and involuntary word substitutions, still get nervous when doing presentations and big talks. The worst thing is actually the anxiety before it rather than the stuttering during it. I can't sleep for days before a big presentation and I get panic attacks with my chest feeling like a knot for the whole week. I know the states have Xanax, but anyone know of a UK drug either from prescription or over the counter that helps with the stutter or at least calms the nerves? I have a massive presentation on Friday and I already can't bear this pain and anxiety in me right now.