My parents live in cyprus and have a uk bank account in gbp. My mum wants to give me 40k do I have to pay tax on this or do I only pay tax on the interest earned.

This would come under Capital Gains Tax as it is over the £10,600 threshold.

More information here: HM Revenue & Customs: (http://www.hmrc.gov.uk/cgt/intro/gifts-inherit-divorce.htm#1)