There's another way to look at this.
You have a 700D, did you get it with the kit 18-55mm lens? If so, why not replace that lens with a better f2.8 lens?
There are 3 main options; Canon 17-55mm f2.8 IS, Sigma 17-50mm f2.8 DC OS HSM or the Tamron 17-50mm.
Part-ex your kit lens with the money you would have spent on the wide angle and you should manage to get at least the Sigma or Tamron.
All of these will give you a wide f2.8 aperture at 17mm (all the way to 50/55mm) which is good and will work well for the Northern Lights. I used the older version of that Sigma f2.8 lens for shooting the Northern Lights last time I was in Norway.
Taking this approach would actually give you a very good general purpose lens as well as something good for low light.
I bought a Sigma 10-20mm f4-5.6 wide angle before going to Norway, I hardly used it. It was almost a waste of space on that trip where I had real baggage limitations. And when you're trekking around in the Norwegian snow covered countryside (esp in the dark) you don't want to be carrying more than you need to.
The other thing to consider is whether the perspective of a wide angle lens will make the Northern Lights appear smaller in the shots than you might want, but it does depend on your view; what's the terrain like, are you high up or are their hills towering over you? etc.
The Sigma 10-20mm f4-5.6 is a decent lens, but even the f3.5 version isn't that great in low light.
The Tokina 11-20mm f2.8 is meant to be a good replacement for the older 11-16mm
Tokina 11-16mm f2.8, older but still very good and if you look at
example images on Flickr, you'll find plenty of low light shots showing it's abilities. Prices should be quite good secondhand.
Samyang has 2 options:
14mm f2.8 and 16mm f2.0 - both fully manual but both meant to be good.
From experience, it can be hard to catch the Northern Lights, just finding/waiting for them is tough. If you can use an app like Aurora Watch, it'll give you an alert when visibility is likely to be best and a general area. If you happen to have some local knowledge or have scouted a location in the daytime, that will make it easier to get a good shot.
I'm heading back to Norway in August, but I'm not sure that will be the best time to see the Northern Lights... can only hope.
Enjoy your trip.