New job

I have been offered a brilliant job, I cannot believe they offered it to me... and it causes problems - anytime I am at work I am so terrible stressed that I behave like Woody Allen in Play it again Sam. And my English is worse then ever - I keep losing words, mixing grammar my voice while speaking is so high that I am likely to be heard by bats... I have to take it easy (easier at least) otherwise they will sack me....but how????? I love that job so much...