You can access it by steamVR, or half life alyx(with steamvr you won’t have access to hl assets), new hammer is a way better than old one, just test it and check it yourself.
Quick tutorial how you can open hammer 5 with steamVR:
Open SteamVR the when it launches click on 3 lines then “workshop” - “create/modify environment” and it should open the workshop tools. From there click “create empty addon” and name it whatever you want. Then beneath that hit show command line and copy and paste it into notepad and delete -vr -toolsvr and just copy and paste it into the thing from the startmenu where you can search for stuff and it will launch the asset browser then you can open hammer 5.
Ah, and with SteamVR you can’t test your map without VR, you can do it only via hl alyx tools.