I would take a look at this thread for some more specific advice: Your personal best way to lose some fat - anecdotes / experiences / examples of what kicked your *** - #73 by konradkowara
I think as you get more experienced you get a better idea of the weekly work you need to do to stay fit, lose weight etc. For me it’s around 5-8 hours on the bike, but starting out I would tackle the weight part head on.