Construct 2 preview mode runs as a webserver, so this should be working.
On your main PC:
1. Touch Win+R
2. Enter "ipconfig"
3. Find the IP-adress for you NIC (network interface card)
On you tablet:
1. Open your browser
2. Enter the IP adress and port 50000 in the address field (ie. 192.168.2.1:50000).
I guess Construct 2 need to be run as an administrator (right click Construct 2 icon and select "run as administrator") for it to work.