"petrified of the repercussions"
No, it is doubtful you are alone. I am not 'petrified' but know there are loved ones who live and work in areas that may be targets. I don't want a 'police state' which each new act of terrorism brings a step closer, nor do I want every movement tracked (already there is a big database recording each person's departure from the UK) but the more 'security' that is added, the greater the lack of being able to go about life without a 'Big Brother' state watching over us.
I'm not in a city. There are no CCTV camera watching me when I go down the street to the shops, and I truly hope that whatever happens, the measures are 'proportionate' to the dangers. I think we have perhaps exceeded that level to date, with proposals for ID cards being a step too far (and fortunately, IMO, reversed). I cannot say I am not concerned about repercussions, but in my view, the worry and paranoia which terrorist attacks cause, and the security build up as a result, actually mean that rather than feeling safer, I fear I would feel I was being 'stifled' by the precautions.
So I am concerned there may be terrorist attacks, but a major part of that concern is the way it will be reacted to (in terms of extra security measures) and probably not the attack(s) if they come (and who will know which were a direct result of last weekend, or would have happened anyway)...
The costs will be high, if security gets boosted, as it is rarely a short-term measure - almost anything they 'add' stays on forever.
I remember being able to walk into the cockpit of a 747 and my nephew went into the cockpit of a plane on a day trip to Lapland, and when I last flew (1999) I didn't need to take my shoes off, nor go through as many security checks, nor have a biometric passport (mine has expired, and they're what, near 80 quid now!), and I could have taken various items in my hand luggage onto the plane (I don't even know what the regulations are these days, I'm so out of touch on this aspect).
We're in danger of frightening ourselves into a self-imposed prison state, not just a Police state, if we react too strongly to any attacks, or even perceived threats. Can one still visit a nuclear power station as a visitor? I went around Dungeness with my brother and mother around 35 years ago but now I suspect that because of security concerns, many technical and industrial businesses are deemed off limits, and military locations, perhaps even some police stations, are given a level of security which may be 'over the top', so we are locking ourselves away against the possibility of some harm, even if it never happens.