The Grammar Goon

In an attempt to better myself as a writer I've been honing my skills.  Or rather I've been trying to hone my skills.  This is much harder than one would think.  My main focus point of late has been my grammar, because I know I put commas in stupid places.  But honestly, trying to get some sort of consensus on when one should use a comma is impossible.  The Americans seem to have one idea, the British another idea and then there are all these folk in the middle throwing commas all over the shot.  Never use and and a comma together.  Always use and and a comma together.  Use a comma with conjunctions, don't use a comma with conjunctions.  I just want everyone to agree.  Why can't we just agree?!  Gah!  I don't know who to listen to and I don't know who to believe.  I'm English and so figure I should be following the British guidelines but I don't know where to look to find an authority on this.  It makes you wish you were at school and could ask a teacher but let's face it, they don't always know what they're talking about do they?  I just want one set of rules that I can stick to and occasionally bend so that I don't look like an grammatically challenged numpty.  And yes I'll use a huge amount of artistic licence with my creative writing but for professional writing I want to have it sorted.  Sorted!  But this seems to be impossible.  I need a guru.  I need someone with all the answers.  Someone I can ask all my crazy questions.  When should I use who and when should I use whom?  Where do I stick all of these pesky commas?  Sometimes I feel like I actually need to go back to school.  My head is spinning.  If anyone wants to volunteer as my guru I need proof of your genius and can offer you a steady salary of fruit pastels.  One per month.  That is all.