National Numeracy is an independent charity that works to improve numeracy, or 'everyday maths', in the UK.  They have created a new website called The Parent Toolkit, which is full of ideas to help you enjoy everyday maths with your children!

http://www.nnparenttoolkit.org.uk/

The Hertfordshire Grid has also produced some resources to help parents and carers enjoy maths with their children.

http://www.thegrid.org.uk/learning/maths/parents/index.shtml