Hi...Can someone help and give me some advise please????

Hi -- Whatever you do, make sure you get a proper visa for your stay. If you're British, you can stay up to six months on a tourist visa; but you can't work for pay on a tourist visa. And if you get caught working on a tourist visa, you'll lose your Shengen status and run into all kinds of other problems.
If you can get a proper work visa from your company, do so. If the company is U.S. based and will be paying you in the U.S., you do need a work visa, even if they don't care. And even if you don't get caught this time, you're likely to face questions next time from customs officials about how you managed a six-month stay without working. U.S. customs officials are not particularly friendly or open-minded (to put it mildly) about anything they may perceive as a violation of visa status.
Good luck. Arizona's a great place; lots to see and do, and lots of friendly people.