We had an inquiry about homeschooling in the U.K. Based upon what I can find, it seems that it's legal to homeschool and you don't need to notify anyone unless you are active in the British school system. (Perhaps in Scotland you do need to register?)
Here's a helpful link: http://www.hslda.org/hs/international/UnitedKingdom/default.asp
I'll post more if I find it, but would appreciate anyone posting their own experiences or those of other expats that they know.