Try TeamViewer. It is a remote control program that will transmit the laptop screen to the tablet. However there are some lags between the screens. I don't know that I would go buy a tablet just for this purpose, but personally have found the tablet has taken the place of my laptop for a great many things. So there you go.
You will need access to the laptop through another monitor to install the TeamViewer software and set it up so that the laptop keyboard and touch pad can control it when in use. After that, whenever the laptop is running, fire up TeamViewer on the tablet and connect.