This pretty much gives a wide selection of what you may get asked for
http://www.goodmusic.co.uk/product/M3166C/...20Dance%20Music (scroll down)
The theme of the dance is actually given beside each track title too

so you don't have to be an expert on what track is a Waltz and which is a Quickstep.
Don't try to mix tracks into each other though. Where ballroom stuff is concerned older generations will expect to be told what style the following track is, in order for them and their partners to prepare themselves for the first steps. So don't just let tracks run into each other like some form of lucky dip, you'll need to announce each track and allow a couple of seconds, also in the future if you ever do a family, masonic or social 'do' and this type of thing gets asked for, they may also want to occasionally change partners between tracks, and I don't mean wife swapping

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The ballroom bits are always a little more formal than other music, where you can just sit back and mix in a few tracks one after the other.