At this time of year where day and night time temperatures differ quite a lot, and with the shortening of daylight hours there is a chance od developing condensation in your conservatory. If it has only been up a few weeks the floor will probably not yet have completely dried out. By leaving the fanlights on lightvent positions, there is sufficient background ventillation to clear the excess moisture away overnight.
Wide variations of heat in the conservatory caused by turning the heating on and off may also cause this problem. Either leave the heat on on a low setting or again, leave the toplights open on the night vent position. Consensation is caused by lack of ventillation and by us breathing, plants in the conservatory and general high levels of humidity. All of these condensation problems can be cured by allowing the correct amount of background air movement.