Hello and thanks for using Just Answer.
My name is ***** ***** am happy to assist you with your enquiry.
You are indeed legally entitled to disclaim your legacy, which I guess is a life interest. You need to do this by the preparation of a Deed of Variation. The Deed, in effect, changes the terms of your husband's Will, post death.
It is a relatively straight forward process for a Solicitor to prepare and is likely to cost approx £250-£350 plus VAT.
Please note the Deed will need to be signed and dated within 2 years from the date of your husband's death.
I hope this assists you and sets out the legal position.