Welcome aboard to the CD Freaks forum
The first thing I would recommend checking is that the 'TV Signal' option in the menu is set to Antenna and that the Country is set to the country you live in. One country may use a different TV standard and broadcast bands from another, so if an option is incorrectly set, the DVD recorder will unlikely scan the band that covers your terrestrial TV broadcasts:
As your TV is connected in series with the DVD recorder, this means that if you can watch TV broadcasts on your TV (besides those viewed through your Sky box), these should be able to be tuned on your DVD recorder. Just make sure that the RF cable going to the RF-in of you DVD recorder is coming from the booster and not connected to the RF-out (in a loop). I have seen something like this happen before.
Finally, note that Sky is recorded using the AV input (as with a VCR). To select the AV input on your DVD recorder, press the 'Source' button on your DVD remote until the Scart input is selected and press 'Enter'.