Taking snacks from home on a flight when you have dietary requirements?

Shalom – I’m in the UK for context.

I plan on flying to mainland Spain this year, from a British airport. I’m not kosher-keeping (I am of Jewish descent though, hence me coming to this subreddit!) but I do not eat any red meat or gelatine for health reasons and am an ovo-lacto-pescatarian. I’ve not flown abroad anywhere since I was 17 and am now an adult (plus it’s only been around five years since I cut out red meat as my issues started post-COVID)

I suffer very badly from “popping” ears during turbulence on flights and used to suck on Haribo to help with this. Since cutting out gelatine I have only eaten kosher Haribo which I buy from a shop in London and have delivered to me.

Would I be able to take these in my carry-on luggage so I can suck them on the flight? Is there a limit to how much I can take? Will there be delays with airport security? Has anyone else in the UK had experience of taking kosher food on a flight who’d be willing to share their experiences?

Thanks in advance!