No, it is not advisable to use STYL single-pack PU varnish, Melmyn or 2-pack PU wood finish over freshly applied wood polish. Any application leads to cracks or peed-offs in a shorter period. As a ground rule, avoid using different topcoats on each other as the chemical composition, drying properties, and other parameters vary from one topcoat to another. Wood polish does not seal the wood but other topcoats might seal the wood. So applying other topcoats on a wood polished surface can lead to instability of the topcoat.