Well the changes I made requires you to be able to compile the client plugin, the files are located in
TVLibrary\TVplugin\TVplugin\teletext
in the file TvFullScreenTeletext.cs look for the function OnPageLoad() here you will find 2 times 2*left/2*top, I changed these to 8*left and 3*top
I didn't center the Teletext, that will probably look better. My guess is the SetPosition(left, top); should be something like SetPosition(5*left, top);
The font is changed in TeletextPageRenderer.cs look for the word "Verdana" and change it, but I am not totally convinced that Courier New is better