Ok, I must have misunderstood you. I'm not so sure the UK would block Scotland from NATO; if heaven forbid, war comes, the UK is going to want to use defense facilities in Scotland. On the EU: since the UK wouldn't be a member it could hardly stop Scotland from joining.
As I said before, other EU states will block Scotland. Net contributors like the Netherland and France don't want to subsidize another failed state. Without English subsidy, Scotland is a failed state.