Caravan Servicing

Hi,

Am new to caravanning and weve had ours just under a year, just wanted opinions on servicing, were taking it to France in summer so want to get it serviced before we go.  Is it better to take it somewhere or get a mobile servicer?  Whats a 'normal' price (weve a bailey ranger 500/5 2003)?  How often do you service your caravan? Any tips/advice appreciated - were in greater manchester