Is there a way to connect to office VPN using parallels (windows) but surf on host Mac OS X?
You may be able to share the connection from Windows to Mac, depending upon how it is implemented in Windows. Follow these steps, from this site:


Add a Host-Only network adapter to the guest (Windows).
Launch the Guest (Windows).
Go to a command prompt and type:

ipconfig /all


Note the IP Address of the Host Only adapter. Likely something like 10.37.129.2.
Assuming the VPN shows as a connection in Windows Network Connections, setup Internet Connection Sharing on this adapter. When setting up ICS, choose the Host Only adapter as the Private Network Adapter.
Once that’s done, connect to the VPN.
On the host, add a route to your VPN, specifying the IP address of the Host Only Adapter as the gateway. In this example, the subnet trying to be reached on the VPN is 192.168.40.0/24, and the IP address of the Host Only Adapter is 10.37.129.2, so in a Terminal window you would type the following:

sudo route -n add 192.168.40.0/24 10.37.129.3