Okay I found the VLANs settings, it was in the bridge interface I deleted in trying to get things working, i've reset to fresh install now. But the isolating clients problem still exists. Or will setting each client to a different VLAN achieve isolation; if so, do I make VLANs first in Router or only in Switch?
I think you will get the best advice if you provide some more info like the make/model of the router and the switch and how many wires between the switch and the router you have planned. Is wifi on the OpenWrt router or do you have an ap that needs to connect through the switch? Do some clients need access to some other but only in one direction - like pc to printer or screen casting to a tv etc? ( That may just be firewall rules etc )
Note that isolating wired clients with vlans may limit the client to client bandwidth based on any limitation of the router and/or a single port if the switch is connected to the router with one cable. I do this and am fine with it but mention it in case you had not thought of that limitation.
Some general advice I would give is to plan out each change and make sure that you maintain connectivity to be able to make the next config change. That goes for the router, switch, and your pc if all the config is via the network. This can be relaxed some if you have serial console access to some/all of the devices. I did mine with a port on each device with connectivity to my pc for management and set up trunking on another port on each device and tested adding one new vlan and new client device at a time for the first couple. With making changes in luci, if management connectivity is not restored within the timeout, the change is reverted and you should get connectivity back to do it the right way after you figure out why the previous try failed. Logread can be your friend on a lot of this.