A basic answer is that they can give you £3,000 in any year and not effect their inheritance tax, anymore and they should understand that the 7 year rule comes into play whereby some or all of the gift may be taken into account for inheritance tax purposes is the giver dies within 7 years. The gift is tax free to you.
See http://www.direct.gov.uk/en/MoneyTaxAnd ... /DG_179336