Retrieve File Custom Field URL

Hi there

I'm adding some custom field values onto a layout override for mod_easysocial_events but I'm having trouble getting the right value back for a File field type. The usual:

$event->getFieldValue("FIELDNAME")

is just returning an array, and if I look at that array there doesn't seem to be anything like a URL, just the id and filename. Is there a specific method please for generating the download url/link for a file field?

I've had a dig around in the component but can't find anything I'm afraid. On the profile page File fields have a link to a download process rather than direct to the file itself and this is what I'd like, or just the URL itself if that's not possible.

Many thanks
Tim