Nearly all of the 'interesting' English channels (i.e. the ones which aren't shopping channels, or similar) are on a satellite which has a very tight 'footprint' focussed on the UK. (Think of it like a spotlight beaming down at this country. Very little of the 'light' would stray either side of the beam). To get a signal from this satellite in Torrevieja you require a dish of around 2.4m diameter. Such dishes cost around �300, plus fitting by a specialist firm (which might well cost as much as, or more than, the dish). I don't know about Spain but, in the UK, planning permission is required for a dish of this size. Then you'd need a digibox to use with the dish. That set-up would enable you to receive a selection of TV stations roughly similar to the traditional UK analogue line-up plus a few extra channels and dozens of UK radio stations.
That system would be vastly improved by the purchase of a FreeSat card. These aren't sold outside of the UK but you could buy one and send it to your sister. They're sold by Sky for a one-off payment of �20. The system would then receive all of the FreeSat channels. The line-up is similar to, but not identical to, Freeview.
There is another satellite which has a much wider footprint. (Think of it as floodlights covering a wide area of Europe). The small dish in the Lidl package might pick up the signal from this dish but, unless your sister is addicted to shopping channels, there's nothing interesting to view.
Chris