Tactics: annihilating the castled king's defences

Hi all, I'm looking for some software or an app that has plenty of tactics practice in checkmating or at least denuding the castled king. This can be 2-4 move shots. I can find plenty of checkmate tactics in an app when the king is in or near the centre of the board or when you are doing back-rank mates, but nothing when you are attacking a castled king from the front when it is behind a wall of pawns.

Also: Can someone recommend an app or software for 2-3 move tactics, e.g setting up forks and skewers? I have Elementary Tactics 1 by ChessKing but the tactics tend to be one-move deals and are too simple. I'm looking for something slighly more complex. Is CT-ART what Im looking for or will it be too hard for me and a waste of money? Thanks for your thoughts. Im looking more for an app than a website, but the latter could be interesting too.

Sorry, this should have been posted in the Chess Books and Equipment forum but I accidentally posted it here.

Giving this a bump.