If you are using VLANs, you can combine the Assessing and Quarantine VLAN if you desire, as they need the same permissions. What you want to do is create the new VLANs and yes, enable routing or ipforwarding on those VLANs. As like with all other VLANs, you would enable the ip-helper to point to your DHCP server, and also add these subnets to your DHCP server. once that is all working, and you can verify that an end system has no problems communicating on the network, you would then lock the VLAN down with ACLs. you would block everything, but permit DNS, the NAC gateway IP, as well as any other assessment/remediation servers you may have or be using (external assessment?) if you are using PBR for redirection you should also allow web traffic with the appropriate DSCP value.