Cheap lens with no coating or only simple coating will hardly scratch. Good UV filter will have anti-scratch coats and antireflex coating so it will not cripple your lens. Cheap UV on expensive lens gives you worst of both worlds - photos like if there is no coating, price tag of your set like there is. And about ten dollars more would give you pretty good filter, highly transparent and multicoated...
with film UV filters are neccary, to prevent in invisible to the eye blue wash.
this won't happen in digital, and there was a thread from a while back explaining that the surface element of a lense is many times harder and tougher than a filter=, and the real amount of protection from physical damage negligable.
Also, dirt does get under UV filters from time to time, and they do need to REMOVED and cleaned.
When it comes to screw-in lenses, B+w (Schneider) makes the best, with Tiffen and Hoya right behind. A lens hood would offer just about as much protection though and would actually be of some other benefeit.
It’s strength is that it’s a good all-around generalist camera/lens combo. A better question to ask is what sort of photography interests you, and is there anything you would like to try that you don’t think your camera would be suitable for? Aside from underwater photography, I don’t see any situations where that kit would be unusable.
The 18-55 kit lens, if it’s the same build quality as they used to make when I worked for the ad agency that had the Canon account in Canada, is not great. I found it produced images with a lot of chromatic distortion and what I tend to think of as “pixel smearing”: the smallest details it produced were 2 pixels by 2 pixels (although it’s conceivable that some of that was sub-par RAW processing, a sub-par digital sensor, or a combination of factors).
If you’re ever in the mood to do any landscape work, you might be better-served with either the EF 24mm f/1.4L or the EF 14mm f/2.8L, assuming those aren’t out of your price range. One caveat, though: since your camera is using a smaller sensor, you might run into vignetting issues (I could be totally wrong about that, but I have noticed that my widest lens produces a noticeable vignette on my camera). Vignetting is easy to deal with in post, and in fact some people actually like the look of vignetting in an image, so that might not necessarily be a deal-breaker.