Just thought I'd update those here on my experience travelling post-notification period as there doesn't seem to be a lot of info around. Previously I've had the usual experiences coming back into the UK as well as a particularly unpleasant experience last year being marched into a room at Brussels as I completed my exit check onto the Eurostar.

I finished my notification period this year and applied for a new passport. My first experience of travelling was recently. Leaving St Pancras I had no checks or questions from the French border control. My wife was ahead of me and did not see any notifications on the border agent's screen. When leaving Brussels I first passed through the Belgian border control (where I had issues previously) and after a passport scan I went through the same as all the other passengers. I decided to go for the e-passport gate (as we all know these do not work for those with alerts) and it worked perfectly and through I went!

I know this is all anecdotal and your experience may vary. I hope to try both planes and the ferry in coming months. Hope this helps some of you looking for stress free travel post notification.