Tail light bulb no power to bulb although rest of light cluster works.. Assuming fuse gone? Yes tried other bulbs etc.. What fuse is it i need to look at. 

Just thinking out loud...

 

If a bulb fails and is flagged power is cut to it.

 

You may need to cycle the ignition and/or exchange bulb to retest for voltage.

Done that.. No power after turning off etc

The rear clusters in the Mk II are known for corroding and failing. Happened on my old car. If you're handy with a soldering iron and tools, you may be able to improve the connection.

 

I believe the slot in bulb holder block that has all the connections in it can be purchased as a spare without replacing the whole cluster. Try Skodaparts? I think they're about £20.

There isn't a fuse per bulb... If you have a fuse issue, it'll probably take out all the lighting on one side of the car 

 

It's likely to be either wiring or an issue with the cluster/bulb.