From what I've been told, lots of people go on to do post-grad courses at Oxbridge/LSE etc from Bath. I would point out, however, for Cambridge at least, I don't think they are too fussed where you did your undergraduate degree, just as long was you did well: eg, 1.1 or a 'good' 2.1. So, you may want to check out first whether people from the Austrian university are able to go to Oxbridge-level universities anyway.
If you're going purely for the international reputation, I'd probably recommend looking at Manchester as well. Grade-wise I don't think it's particularly difficult to get into (at least for UK students who'd be applying to universities like Bath), and it's ranked within the top 50 in the world.
Also, consider what particular course you are taking. There are certain courses that Bath excels at nationally/internationally, such as Management. I know Bath runs an MBA program as well, I believe it was ranked in the top 20 in the world. This may be the case for your particular course, in which case, Bath would definitely be worth it.