Hello Sarah,
The law is quite specific. You must not tow a trailer that has a mass greater than the MTPLM limit stated by the CAR manufacture. The Chrysler Voyager is rated to only 1600Kg and that limit must not be exceeded. To do so is illegal, and your insurance will be void.
Your suggested combination does raise my concern. I am not familiar with the Swift, but if it is rated to 1741Kg - maximum, then you cannot tow it fully loaded. - However, if the caravans Mass in Running Order (i.e. ex-works with no added items) is less than 1600Kg, then you can tow it, but my suspicion is that you will very quickly approach 1600 when you have added gas bottles, battery and all the other items.
Do not be fooled by other caravanner's who tow bigger vans, the chances are that they are actually illegal.