In my experience it is not that simple.
Generally TV Cards have a Application included that you run to tune it. This will only tune the Default channels on certain frequencies (remember most of the Country is on Digital Signal now) you cannot program it in using the old fashioned "moving a bar along till it looks right" method.
It also depends on the sky box, does it even have an Aerial Cable port??
Should work absolutely fine. I use a standard coax aerial cable to connect my HD box from downstairs to my TV upstairs because I don't use it upstairs often enough to warrant getting a second box.
If you want to be able to change channel you'll need to get a magic eye, enable RF power in the options and use the RF2 output socket to link to your TV tuner. As long as you get an analogue TV tuner card then you'll be fine.
Of course, when using RF you won't get HD quality but it'll do the job.
If you want hd then you'll need an old sky+ hd box with component out.