For ePub, you are better off using Calibre to convert from ePub to MOBI. This is because ePub and MOBI are relatively similar reflowable ebooks formats. Savory is Calibre hosted on the Kindle, and it is generally easier to use Calibre directly on a Desktop PC.
You would first need to strip DRM (
Adobe ADEPT DRM for EPUB circumvented). In the UK, I don't think stripping DRM adds any extra legal issues although format shifting of copyright material is not allowed (a fact that is universally ignored).