You should keep the original signed Will, and store it in a safe place. It is also beneficial to explain to the executor where they can find the original Will, as it is required by the Court after death to obtain a grant of probate.
You can also upload a copy of your Will to your Safewill account as a backup. If the original is lost, your executor can contact us to access the most recent version of your Will, so there is always a security net that traditional paper-based Wills do not have.