My Liteon HDD/DVDR lets you "pause" whatever you are watching either on HDD or DVD RAM. Not sure how Sky+ works, but with V+ it automatically caches what you are watching, so you can "rewind" automatically - none of the standalone HDD boxes I have seen offer this functionality.
Having Freeview doesn't make any difference - if your Sky box has a SCART or other compatible output, then you will be able to output a signal to an HDD recorder. (Some programs/channels like "pay per view" may have encryption that does not allow recording).