In reply to luckywood:
As others have said the technical stuff isn't the issue. Lots of good climbers brought up as rock climbers find they can't really hack it (not a technical term) on quite easy routes in the Alps. The essentials include:
1. Considerable physical endurance, because they are often long days and tiredness leads to carelessness and accidents (like minor slips) which would probably be trivial in, say, the Lakes, but anything up to lethal in the Alps.
2. A steady head on you. I've always thought the main problem with the Alps is that they're steadily falling down, so loose rock and poor rock are a given. This can make quite easy climbing rather serious and whether this worries you a little or a lot (and it should probably worry you a bit) will have a lot to do with whether you take to Alpinism even of a low grade. Even easy routes can be too stressful for some people to enjoy.
3. Patience can be useful too on honeypot routes like the Hornli Ridge. You have to expect crowds and other people there to be inexperienced (being guided), slow, clumsy and likely to knock rocks down on those below.
Before doing something like the Hornli Ridge you really need to get some experience on more trivial routes, where you'll find whether 2 above is likely to be a problem for you. If you just want to do the Matterhorn in isolation and then get back to sport climbing, I'd hire a guide.
Post edited at 17:17