While Roku does support screen mirroring, I've only done it successfully from an Android phone. It can be done with Windows 10, but has very stringent hardware requirements (not Roku requirements, but Mirrorcast) to make it work. Many people that have made it work later report it is hit or miss. For iOS devices, there are supposed to be some apps that work, but I've never tried any.
If your laptop has an HDMI out, it would be much easier to just connect it straight to the TV.
Nvidia Shield, Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.