Like most VAG cars, there are 4 strong points on the body, more inboard than the folded sill areas, each of these 4 points on the Polo/
Ibiza/Fabia/A1 has a round nylon blanking cover - as opposed to black "rubber" covers/bungs, if your trolley jack has a compliant pad on top or built into the saddle, you can centre the trolley jack at each of these points to fit a jack stand or axle stand under the usual "emergency car jack" associated to that jacking sill/rail position.
I tend to always play safe so place a wedge/stop at the front of each front wheel and at the rear of each rear wheel to minimise the risk of it moving while jacking.
Plus, you can always go to the expensive of fitting Audi TT Mk1 "jacking point protectors" at each of these 4 holes in the body - and just place your trolley jack under them when jacking up - I did that to my wife's previous 2002 VW Polo and have done the same to her current 2015 VW Polo, these 4 areas are easily strong enough to be used on these small cars only, I'd not bother trying that on Golf/Leon/Octavia/A3 though.
As an "information only" comment, there is a version of trolley jack available that has a notch in the lifting parts so that you can locate axle stands and the trolley on the folded sill strong sections at the same time - but as usual only available, I think, in the USA. Similarly there is a more expensive option, that I felt the need to buy, that consists of, in my case, a set of 4 cast alloy "stools" that have a detachable top plate, you place the top plate on the trolley jack, just up the car, slip the stool in so that it is now under the top plate, then lower the trolley jack and you can remove the trolley jack, I find it smarter to use 2 trolley jacks and lift one side of my cars up at a time - that kit is called Jackpoint jack stands, again only sold in the USA but I joined a Porsche group buy so the shipping was very cheap as maybe as many as 10 or 12 pairs of jack stands were being ordered in at the same time - so we got discount on the jack stands as well, still quite expensive though, but I've used them on our Audi S4, SEAT Leon Cupra, SEAT Arona and VW Polo and they make doing brake work very easy as well as any other jobs that require the car to be lifted up off its wheels. I made up 4 long wide wooden ramps for when the work being done does not need the wheels to be off the ground.
Edit:- I've seen these comments/videos concerning lifting Golf GTIs "from the other end" but I've never got the feeling that a Polo/
Ibiza would cooperate in that way, yes lifting the front will lift the back quite quickly, but not the other way round. My old S4 has "firm" suspension, but I'd never try that trick on it.
I always aim to just use the folded welded seam/sill/rail - at the jacking points, to locate the jack stand or axle stand adaptors and use the strong areas at these points to carry the weight of the cars - so far so good!