(Warning: I'm in overshare-mode)
As Ilovemykids said... Tx is super easy legality-wise (EVERY state has different HS laws)... but in Tx all you have to do is unenroll them, at ANY time. No timeframes, testing, academic plans, or bureaucratic hoops to jump through in any way. ((All my friends is Tx *gloat* about how easy it is :)) So it's as easy as putting on a big smile and signing them out. NO ONE has the legal right in Tx to tell you otw. Read through that link she gave you.
And here are a couple more for support:
http://groups.yahoo.com (tons and tons of great groups out there, local ones for fieldtrips... to national ones for special needs / 2e/ gifted/... curriculum groups/ hs philosophy groups... religious/ secular... 10s of thousands of us on hundreds of groups. Here are a few specific ones you might be interested in... but there are a LOT more out there :)
http://groups.yahoo.com/group/ADHD_Homeschool/?yguid=4070... (since from your profile one of your kiddos is like mine)
As far as curriculum goes, that's another matter :) I tend to think of curriculum as the "fun" part... because we ALL use different curriculum. For our (adhd) family we do about a 40/40 split between montessori and charlotte mason... with the other 20% being totally eclectic (like "Minimus, the Mouse that Made Latin Cool!" for latin, ClueFinders for some of our math stuff, NetFlix's amazing documentaries - everything from Walking with Dinosaurs from the BBC to H's The Universe, to Engineering an Empire... tons of amazing things). You'll find most of us with special needs or gifted kids tend to be on the eclectic scale, because the whole "school in a box" thing just doesn't work for *most* of us (of course, it works for some, just not most).
2 good sites to explore as far as curriculum choices:
And... because I'm feeling all perky this morning (and all I have to do is cut and paste ;)... here's some of the curriculums we use. Use anything for idea generating... not a "should be" kind of thing. Like I said we ALL do different things. Finding what works best for each family is one of the most amazing gifts of HS.
http://www.freemontessori.org/?s (check out the albums link on the right)
and 2 unit studies we're doing science-wise this year:
http://www.borenson.com/tabid/933/Default.aspx (for algebra, because I've got a "numbers guy")
Unit Studies (we go by civilization... right now we're in Ancient Greece)
Mens sana in copore sano (aka our school motto "Healthy Mind, Healthy Body"; Sports & Activities beyond daily playing with the dog, gardening, tree climinging, bike riding, etc. On average we spend 4-7 hours a day doing super physical play... but do remember, we're an adhd house, so we do LOTS of active stuff)
Fall : Gymnastics & Soccer
Winter : Gymnastics & Snowboarding
Spring : Gymnastics & Baseball
Summer : Swimming & Sailing & Surfing
If this all sounds super-busy/ kinda over overwhelming/ expensive... know that on average we do 4 hours of school a day... a lot of play... and spend around $100 - $200 a month tops, and many months we spend nada. So it's all actually really relaxing. LOL... actually we don't even usually get UP until 930ish most days, and school starts typically around 1030.