By default the forward skip is set to +2 mins and reverse skip is - 5 seconds. Your 1100S may have a different remote. On the one that comes with the the HDR-1000S they are under the text button (forward skip) and recordings (backwards skip) at the top of the remote. If your remote is different the symbols will be the same.
Forward two right facing triangles with a vertical bar on the right end, Backwards is mirror image. The same keys used to skip forward and backwards in the epg.
Most ads are 4 mins so two forward works with any slight overshoot corrected by the reverse skip.
The default durations can be changed in settings.
Don't expect them to work on LIVE TV unless you have paused the live stream long enough to build up a buffer. The capability to invent content not already transmitted doesn't exist.
Try this set up a recording on ITV-HD say starting at 19:00. Watch another channel or recording for 10 mins or so. Now bring up the media list and select the entry for the ITV-HD programme currently recording and start to play it back (chasing playback). When the ads come on press the forward skip keys (twice for most ads). You will finish watching about the same time as the actual programme finishes. When you get less than 2 mins before real time the forward skip keys simply stop working. Don't be tempted to use the right keys as you will be dumped out of the timeshift buffer to real time and have to resume the programme playback to get back.