I used to live there 20 years ago since I am a grad of Coastal Carolina Univ. but I did more running while I was there than fishing. However there are a number of fishing piers up and down the grand strand. I used to live by the one in Surfside Beach. It is a nice pier that gets you outside the surf line and fish can be caught.
If you look at a map at the Cherry Grove beach area you will see small inlet. This is a great spot especially at low tide. You can also rent a kayak and fish the Marsh there as well. All sorts of fish in that inlet depending on what time of year you are there. The Gulf Stream head boats will also get you on a good catch that won't break the bank. Good luck!
Those are the waters I grew up fishing. March is kind of early to say the least. If you want to spend some family time and do not care to catch/catch anything big, go to Apache pier and soak some fresh shrimp on the bottom. You will probably catch some whiting. Pompano and bluefish may start making a move into the area. By mid-April, much of the inshore gamefish have returned. Late March is simply hard to predict.
If you really want some sort of "serious fishing," take a charter. The nearshore/offshore fishery should be getting decent.
The most reliable fishery would actually be the blue cats of Santee Cooper Lakes. Many guides down there offer no fish no pay policy. Another reliable fishery that will require a drive is the American shad run. 8# spinning tackle with 1/8 oz jigheads and 2 inch grubs will have you hooked on fish 2-5 pounds each from shore. PM me if you are interested in that.