Do impaitents come back every year?

They are frost tender, but if you take some cuttings and place them in water they will grow roots, pot them up and keep indoors till after the frosts are finnished then plant out again.

I would have said no, not if you don't take cuttings. Lots of LGC will be selling them later on in the year, or you could always buy packet of seeds now and see if they are successful.