Welcome to the forums,
ooptea.
The problem with a font is that there is no normal skywriting lettering. Some have a series of dots, some write in capital letters, some try for script. In trying to answer your question, I tried to figure out something which people would instantly identify as skywriting and was within your capacities.
I came up with the idea of using one of Nagels Cloud Brushes. You can download them here.
graphicssoft.about.com
Once they are downloaded, place them in your Presets > Brushes folder. Once there, you can load them into your brushes palette by using Edit > Preset Manager. Here comes the only really tricky part. Even though you've loaded the brushes, you have to use the Brush palette to set the brush up. For example...
You might want to use Nagel Series 11 Jet Trail 3. Well, straight out of the box (so to speak), it might not be perfect but you can adjust it in the Brushes palette. You have to get the Brushes Palette on screen. It might be in the Palette Well or you can get to it by Window > Brushes. Once the palette is available, I might start by clicking on the words "Brush Presets" which brings up a palette identical to the one you can access from the tool bar. There I would select the brush and change the pixel diameter which would work best.
Next I'd click on the words, "Brush Tip Shape," and change the spacing to about 40 or 50%. Then I'd go down the list of checked items and look at the different settings. The scattering is pretty good for a skywriter, I think. Color Dynamics change the brush color from the foreground brush to the background brush. You could well start with a standard white foreground/black background colors (just hit the D key). If there is too much gray, you could change the background color to a very dark blue/gray and modify the Foreground/Background Jitter in the Color Dynamics panel.
Once you have your brush set up (experimentation is in order here) you can just draw your text using the brush. Here's a little sample I did...
Skywriting 
Linear Mode
