Steering probs

I have a 1.0 1998 'R' reg polo. Over the past few months the steering has become increasingly heavy. It's fine on the straight, at speed, but try steering it into a parking space! Tractor comes to mind!

I bought some steering oil but can't find a reservoir anywhere. In addition, the car doesn't have power steering, and so I'm not even sure it needs steering oil.

Can anyone help to either confirm hydraulic oil is needed or suggest another solution.

cheers
A