'Income bands' in tax credits - can anyone shed some light and stop me getting into trouble.

[MuchoConfusion]

DH's business did very poorly 07/08 and even after my part-time earnings were added, we are receiving a lot of help from child tax credit/working tax credit for this year. Our income was less than £7,000.
It looks like his earnings will be slightly more than last year and our total for the 08/09 year will be just over £10,000.
Is this going to put us in a 'higher' income bracket thus reducing our CTC/WTC and ending up with us having to pay back some of what we've received this year?
If so, I need to be proactive and start putting it aside - from where, I don't know!

Tax credits are usually done on the previous financial year's income unless you earnt LESS than the previous year or 25K MORE than the previous year. So you can earn up to £25K more than the last tax year without it affecting this year's tax credits. Next year they will take into account the higher earnings.