If you are very sure that your taxable income (after personal pension contributions and charitable donations) will exceed £60,000 in the current tax year, then you should probably opt out of the Child Benefit system. If you think there is a chance your taxable income will be less than £60,000, then you should stay within the Child Benefit system.
You can stop or restart your Child Benefit by an online form at the HMRC website, or by calling the Child Benefit Helpline. If your taxable income is less than £50,000/year then you can spend all of the benefit. If it is between £50,000 and £60,000/year, you should keep some aside for repaying HMRC once your tax return has been submitted.
Ways to reduce your taxable income (and potentially qualify for more child benefit) include paying into a personal pension scheme; and transferring deposits and investments to a spouse. Also, if you have your own business, you could discuss with your accountant possible ways to reduce your income or move it into a lower earning tax year.