Do yourself a favour and fit a 2nd drive. An encryted 3TB drive will give you plenty of redundancy and it would be good to have an external encrypted back up for the must never loose files! It will be slower to access than the SSD, but means space is never an issue.
Toshiba P300 3TB 3.5'' SATA High-Performance Hard Drive (OEM) - Ebuyer
PS. Windows should automatically run trim (Windows 7 up) on your SSD, make sure though that de-fragmentation is turned off.