Starting a temporary job

I receive carers allowance (for my 6 year old severely sight impaired daughter) and haven’t worked since she was born.
Now she’s in school I have been looking for part time work.
I have been offered a job that is a 3 month contract but with the potential for being extended/made permanent.
My question is this…as I would be earning over the carer’s earning threshold I am aware that I need to advise them that I’ve started work.
But what happens if the contract isn’t extended?
Can I go back to claiming CA after the 3 months?

Also, I receive child tax credits - I understand I will also need to let HMRC know I’ve started a job and that I will loose the CTC - can this be re-applied for if the work contract doesn’t last beyond the 3 months?
If the job turns into something permanent then great - I’m happy to loose all the benefits.
But I don’t want to accept the position, finish after 3 months and then find I can claim for anything again.

Hope all that makes sense!

Read up about all the allowable expenses for childcare and pensions.
It is better to spend £20 a week on pension contributions, to keep you below the income level, then you are still £100 a week better off!