Sky Sports is an amazing network of sports channels, and in general they do broadcast all sorts of sports, including rugby. That is why I am curious as to whether they will broadcast the Rugby World Cup as well, or will I need to watch this some other place (and then I might not subscribe to Now TV Sports after all)?
I would clearly recommend a NOW TV Sports subscription anyway, but the Rugby World Cup will not be broadcasted on Sky Sports/NOW TV. The tournament is hosted by England and the matches will be played at different stadiums in England, but unfortunately it is not Sky Sports who carry the rights to broadcast in the UK, but instead the TV channel ITV has the rights to broadcast from the rugby world cup. What might though be positive with this, is that ITV does not require a plus subscription for you to watch, so you can watch it for free online, but if you are located outside the UK you can visit itv.fromabroad.org to find out more about how you can watch ITV online from outside the UK.
If you want simply more information about the rugby world cup and take a look at the schedule for the tournaments, read about the different stadiums and so on, then the following site can be warmly recommended: www.watchworldcup.net
The rugby world cup will start on September 18th and the opening match which is 9 days away from us at the time of writing will be played between England and Fiji. So, get ready and have fun, and if you later want to watch some Premier League football as well, then do not forget that you can watch almost all Premier League matches on NOW TV with your Sports pass.