Deep down I know that for my current circumstances I could afford to take some of my ISA income rather than deny myself a few extra luxuries and leave all the income accumulating to end up in my estate when I die. I am however still having some difficulty clearing that mental hurdle that Scott mentions and actually setting up a regular monthly withdrawal. I keep telling myself "maybe next year" but next year comes and I don't do it. If anyone has been in a similar situation and has any advice about mind games that they played with themselves to help get over that hurdle then I would be interested to hear them.
I have a SIPP in payment but 2 ISAs still building. Taking some income, while the bulk is still growing, is quite comforting.
You could start by taking a small monthly income from your ISAs, perhaps up to half, but you would still have quite a bit to reinvest and grow the capital. You would still have the pleasure of choosing where to put that remainder.
Enjoy some of it!