The "Flight Computer" is essentially a round slide rule. I remember my large slide rule being my pride and joy at school. I quickly dumped it when Clive Sinclair's calculators came within financial reach. The rest is history.
Quite why the CAA are wedded to this device is quite beyond me. Like any mechanical device it is prone to user and reading errors and because of its logarithmic scale it is more difficult to read between 9 and 10(0) than 1 and 2! The wind scale on the reverse is similarly prone to error. To argue that it is an important skill to be able to use one is like saying that doctors should still know how to bleed people or motorists how to manually advance and retard their ignition. The argument that it has no batteries to wear out is a complete nonsense as an electronic flight computer is inherently far more reliable and less error prone and will only be used on the ground where if the thing dies you will have access to many alternatives anyway. Furthermore, no one uses it in flight as it requires more hands than any of us have and put your head inside the cabin for too long when it should be looking out.
I have given up putting in a wind calculation into the plog as winds are never what they are forecast to be (I did on a recent trip via Skydemon and the resulting heading was way out!). The skill is in assessing the effect of wind on your track and compensating as necessary; the amount of compensation will vary during differing parts of all but the shortest of trips and of course it will also change both in direction and speed if you are forced up or down from your planned altitude.
The reality is that as the vast majority of people now use a PC for Wx and Notams a substantial majority in all probablility use it for their flight planning as well. When you have things like Skydemon light for free why would you rely on a difficult to read protractor for tediously making up your plog? That is not to say that you don't use a chart. Not only must you have a chart but it is essential to plot a line on it and to know independently of GPS where you are. I now plot the line from the date produced by the electronic plog and mark the headings on the map from the plog along with six minute timing markers.
Learning with a flight computer is not "learning properly", it is making life difficult for yourself by using an inaccurate, inherently error prone device which the rest of the world gave up on 40 years ago. The worst thing you can do is copy the data from a flight computer into your plog and then slavishly follow it irrespective of actual conditions.