Map updates are usually NOT free. Some manufacturers allow for a "one time update" within 30 days of purchase - to ensure the owner of the latest maps. Other than that, there are three models out there.
One is a the purchase of individual map sets for the geographical area of interest for a modest fee. nearly all manufacturers offer this type of update. In return, a disk containing a program to update the maps in the GPS is run on your computer while the GPS is connected via USB cable or serial cable. You might even end up maps preloaded on a removable memory card. Simply inserting the card into the slot on some GPS units will allow the the GPS to use the new maps on the card instead of those installed on the internal memory of the GPS (if the memory card is removed, the GPS uses the old internal maps).
The second model is a map subscription service (Garmin and a few others) that allows for the download of new mapsets as they become available (2 or more times per year) to your computer. This is done on older models (those sold before lifetime maps were offered) or if it is determined that buying updates one at a time will be too costly, after purchasing the GPS. Running the download with the GPS connected to the computer will update the internal maps of the GPS - just like the disk method. The subscription service costs more than buying a single update disk, but is often less than the cost of 2 update purchases. The subscription lasts a predetermined amount of time, or in many cases, "for the life of the GPS".
The last is similar to the subscription method above, only that you purchase the GPS with lifetime map subscription built in to the cost of the GPS. Included in the GPS package are instructions on how to go about starting the subscription and installing the maps - the same instructions are included with the purchase of a subscription after purchasing the GPS.
One place that sells maps for the Navman brand GPS can be found at http://www.activegps.co.uk/navman-maps.htm
You may also find them available for sale in retail outlets that sell the Navman GPS devices, too.
Speed or "Safety" cameras and Red Light Camera locations are often offered as a subscription, due to the not necessarily permanent placement of these devices. Some manufacturers offer this, while others do not. Third party providers have stepped up to fill the void created by those that do not offer this information. I found these sites that have this data available: http://www.pocketgpsworld.com/uksafetycameras-navman.phphttp://www.speedcamerasuk.com/speed-camera-database.htm
There may be others that cost less or are even free. Keep in mind that maintaining this database can be difficult, so the free databases are more likely to have erroneous information in them when compared to those databases that charge for access.
I hope this was a good starting pint for you and helped. Please rate my reply - thanks!