I suffer from similar problems when sitting on public transport. People eating, coughing, sneezing, making phonecalls etc. Horse stables…
I also live close to a flight paths and almost went completely mad.
BUT…. I found one type of ear protection that’s very powerful. It’s not active but the insolation is soo good in it. Actually they use these on airports 3M Peltor X5.
Go buy one on ebay it will cost you 25 GBP and you will find yourself very very comfortable in the office from then on.
If they actually buy the noise cancelling ones for you you can still use the 3M for commuting or anything else.
Pls don’t hesitate buying them….
Let me know how they work out for you.