A lot of the stuff people say we should be doing is already being done. Think its important that we react in an appropriate manner though according to the laws of this country.
Death penalty - its not on the statutes any more which to me is a good thing. Dont think it has a place in any civilised society.
Revoking citizenship of terrorists and terrorist sympathisers - sounds great but only applicable where they weren't born British. The British ones are our problem and we need to deal with it ourselves. Its an uncomfortable fact that someone born and raised in UK can still feel that disaffected with civilised society that they are willing to die for some extremist ideal. We need to look at why that happens and deal with it through education and integration. The vast majority of Muslims in UK are not radicalised and feel part of UK society. Govt needs to pay more attention to why radicalisation happens and how to combat it without making the problem worse.
Border control - think we already refuse visas for anyone with an ISIL passport

and you cant do a Trump and decide that all country's citizens should be labelled terrorists just because some have come from there. We already have some of strictest border control in world. All Brexit will do is allow us to control EU citizens coming here to live and work. Suspect it will make very little difference to short term movement of EU citizens in this country. Just hope it doesn't actually reduce security by reducing cooperation between various European intelligence services.
These events are horrific but what sets us apart from the people who commit them is how we react to them. If we overreact the terrorism has actually achieved its goal.