The speaker is such a good actor that he can even fool himself. First he demonstrates his acting chops by pretending to be drunk. He's like an alcoholic who would do anything for a drink, except he wants a drink that contains the essence of the south of France and the Mediterranean sea coast. He stumbles around like the person who has had one beer at a party and starts shouting, "I'm so wasted!" But this act isn't enough to convince himself that he has really consumed this special drink, so he uses his own poetry to create the illusion that he has left the world behind.
The speaker is definitely a poet because he tells us so. Lucky for him, playing with language does the trick, and he manages to convince himself that he has been transported to a completely new setting and perspective. Unlucky for him, he commits an amateur mistake: he flubs a line. He wasn't supposed to use the word "forlorn!" (line 70). This word breaks the spell of the performance, and he recognizes that the nightingale has flown away.
The speaker must be under a lot of pressure if he wants to leave the world so bad. Actually, he's down on life as a whole, and at a couple points you might worry that he'll try to end it all. But we're never fully convinced by all his talk about how easy Death will be, and we don't think he's convinced, either. It's all just a show. Also part of the show is the speaker's display of his knowledge of Greek myth and the Bible. He's well read, with an active imagination, and he wants you to know it.