Personally I think the right to life is more important than minor breaches of the right to privacy (governments reading the emails of terror suspects would be a minor breach, the fappening would be a major breach imo). Anything reasonable that makes it more difficult for the terrorists to operate gets my support.
As far as I'm aware, there have been less than 10 deaths in the UK due to terrorism since 7/7 (10 years ago). A similar number have died in elevator accidents.
If it does, I'll cross that bridge when I come to it.