First off, if you're totally new to multihulls, then an F18 probably is not the best type of boat for you to begin with. A good analogy would be trying to let a teenager learn to drive with a Ferrari. F18's are expensive, complex, overpowered, and unforgiving. There are a lot of other beach cats out there that will provide plenty of performance and are much better suited to someone just starting out.
As far as sailing an F18 solo is concerned, you also need to consider that rigging and moving the boat around on the beach will require considerably more effort when done alone. For the occasional trip, it would certainly be possible to sail an F18 solo in the right conditions, but if you plan to regularly sail solo, an F18 would be far from ideal.