This two tap hole bath filler from the practical Opus collection offers an intuitive upgrade for a set of pillar taps. Installing this bath filler will allow both hot and cold water from a single spout as a single blend of water.
If a bath filler doesn't offer enough functionality, there is always the option to add a shower mixer to it. This adds an outlet on the spout which connects to a hose and handset. Simply pull the lever on the spout to switch between the different options. A far cheaper solution than installing a separate shower.