Yeah that's what it was the Cash needed spending!
Found another good app (switches tablet on to find out what it's called)
Magic Doodle Premium
Very competent painting/sketching app with lots of custom brushes and a very nice colour pallette selection menu, groups of colors like: skin tones, acrylic, marker and many more.
It also allows you to input the specific color numbers rgb/hsv or hex. Also has a grid feature and playback of your painting.
Another one not mentioned:
Andrawing (standard and pro versions)
This one is a little different though still quite good. The diffrence is in the initial menu options Kalidescope/kids/draw/draw on picture. Kalidescope is a novel way to sketch but I'm not sure it has many applications lol.
Kids is for uh kids (not tried it)
draw and draw on picture are identical other than the latter loading a picture to paint on. As for options there are a range of options including text, clipart lol (Quite good clipart) A basic but functional colour pallette.
It's not what to sketch or do it's the love that we give to you.