Tax Code

My tax code is 0TM1.  This means I do not get a personal deduction  .  Is this right? 

THe HM Revenue and Customs page says OT "Is used when your allowances have been used up or reduced to nil and your income is taxed at the relevant tax rates. May also be used if you've started a new job and don't have a form P45 or haven't completed a form P46 before your first pay day"

Can I change my tax code? 

I seriously feel my adrenal glands working overtime whenever I think of taxes. 

I gather I need to fill out a P46 (gosh, I hate HR).  Will this change my tax code? 

Update:  All I had to do was call HMRC.  They updated my tax code and I sent my P60 to them so they can adjust my taxes owed versus paid. 

Update:  All I had to do was call HMRC.  They updated my tax code and I sent my P60 to them so they can adjust my taxes owed versus paid. 

Yep, it's nice and easy .

I was on the wrong tax code for a year without realizing it and I overpaid about £2,000 in taxes. All I had to do was call HMRC to change the code and within 4 weeks I received a cheque for £1,500 for the previous tax year, then I got a tax refund in each paycheque after that for about 8 months until I had received all the overpaid tax back.