It is an extremely important legal document and needs to be kept in a safe place, but we will leave the choice to you. That way, you have control over what happens to the document during your lifetime and you do not have to commit to any expensive storage options which may not be as secure as advertised.
We recommend keeping the Will in a fireproof box and storing it somewhere high up in the home to avoid the risk of flood damage.
It is also a good idea to tell your Executor(s) where it is being kept so that they are aware when the time comes. Another option is to store your Will at the Probate Registry for a one-off fee of £20.00 (March 2017), see form PA7 at http://hmctsformfinder.justice.gov.uk/HMCTS/GetLeaflet.do?court_leaflets_id=1033 for further information.