Olly,
A tough enough finish can be obtained using the method I use, either with a mix of oil and varnish as in my pic above or just varnish. Trick is LOTS of thin coats dried and flatted between each coat and gradually built up. This penetrates the timber and remains flexible, instead of forming a "plastic" skin floating on the surface of the workpiece.
My wife dropped a 2lb scale weight from a high shelf on to a table I finished this way and the dent was sharp and over 1/4" deep. But the varnish never broke, remained intact.
A fresh brewed pot of tea could go on it, or an overheated plate from the microwave and not cause a problem. Maybe just some local condensation under the crockery! But never penetrating the surface.Table surface is still intact after 20 years growing family abuse.........