That just DISCOURAGES folks to ask more questions because they think their questions might be regarded as "stupid".
Exactly what I was thinking too. There are a whole load of nuances and variances european wide that probably dont make themselves particuarly clear in the training material. Thats why people come to places like this for 'opinion' and to one day aim to explorer the wider world.
As others have said, there is nothing illegal there, but unless you have an IR, or in the UK an IMCr or an IR(R), I would be very careful about overflying a destination that is fogged in, especially if a) it was going to be a planned or even unplanned alternative b) other airfields are reporting low viz / low cloud. Worse case, you might have to use some of your instrument skills to aid you in a safe landing somewhere. It is a judgement call but fog will either get worse, or better, but its a gamble which way it might go. It probably wont lift when the TAF says it will either ;-)
There was an incident here in the UK a few years ago where the TAF's had almost no claims about predictin of fog, and mid afternoon, and an amended TAF later (no use when you have already taken off), almost the whole of the south east quarter of the UK was a big sheet of fog, causing at least one fatality if my memory is correct.
So good on you for asking the questions and seeking opinion, and always be careful.