If its a fit and forget safe, avoid the digital ones the batteries run down and then you find youve lost the key to over ride the mechanism.
You just hold a PP3 to the contacts to power it and enter the combination.
However, it’s quicker and easier to just use a magnet to open them (works on about 99.9% of electronic domestic safes and leaves no sign of entry).
[video]https://www.youtube.com/watch?v=u3p5KUNfDG0[/video]
http://lock-picking.wonderhowto.com/news/safe-cracking-made-stupid-easy-just-use-magnet-0168427/
You also don’t need to worry about the deeds, they’re completely worthless* and you can always request a fresh copy from the Land Registry for a nominal fee.
* a very small number of properties or land may not be registered but if you bought your house in the last 100 years, it will be.