That's not how it works. You'll get the tax free part of whatever amount you put into drawdown paid straight away. So if you put £16760 into drawdown you'll get the lump sum of £4200 paid to you then if you take £1047/ month that will use up your tax allowance for the year if that's your ONLY income.
You could put any amount you want into drawdown and you'd get 25% tax free of that amount and still just take £1047/ month and if that's your ONLY income you'd pay no tax. I wouldn't do this but some do to buy a car, pay mortgage off etc
Regarding the funds in drawdown. You could put the money into exactly the same funds as you had before so you won't miss out on any growth, but as ever depending on what happens to markets you could also lose a canny bit. I wouldn't do this either