From April 2008 the weekly rate is £50.55. Sometimes you can get an extra £30.20 for a dependant adult. If you have dependant children you can claim for them by claiming child tax credit. However if you have been receiving CA continuously since before April 2003 you will continue to receive additional amounts for your dependant children as part of your CA claim.
For further information regarding tax credits select the link entitled families and benefits on the right side of the page.