In that case, maybe get a cover and definitely not real rattan, because it will rot. You can get rattan effect stuff that is plastic, but it's not nearly as nice and I worry that it would be hard to clean.
Yeah, a hardwood would look great and give you more robustness. If it weathers a bit, it'll still look decent rather than doing that awful thing that plastic does when it's kept outside of changing colour slightly. Bear in mind that it has to be treated every year to keep it looking good if it's outdoors all the time, even if it's teak - but this is not an arduous job - think an afternoon pottering with a paintbrush!
I have the smaller folding table (my patio is tiny!) but I covet the one that seats 4-8. It has two folding end sections
I would personally choose the folding ('recliner') style chairs over the armchair type/ benches. They're a bit more space saving when not in use and still comfy. I can lean them against the table or in the shed too over winter.
I've seen the set on eBay locally from time to time so worth checking.