Chil Benefit and Chil tax credit - Family travelling

Hi
Please can you advise on this

We are all British Citizens. My wife along with our 2 kids is travelling abroad and most probably will be staying out of UK for more than 3 months, My mother in law is not feeling well and since my kids havent started school yet My mrs want to stay there and look after her mother until her medical procedures and treatments

We claim Child allowance and Child Tax Credits. do we need to stop these before my wife travells abroad? or can I call and inform HM revenue and Child benefits team later? Also, how many days can my family be out of UK to keep claiming these two benefits. I am in a full time employment and will still be staying in the UK

Your advice will be much appreciated

Regards
Faz

child benefit
inform them if they go abroad permanently or for more than 12 weeks.

Tax credits
You must tell them straightaway if you, your partner, your child or children or all of you leave the UK:
• permanently
• for an absence that is likely to last for more than 8 weeks when you leave.

read this

http://www.hmrc.gov.uk/leaflets/wtc-fs6.pdf