Security is decent if you find the right company, I could help you out.

Civil Engineer (Construction on the Motorways etc)

Restaurants and Retail are always a smart choice at a young age. Good experience to put on a resume and you can meet references for future jobs.

Fast food places are normally the best place to start off at, minimum wage has gone up a decent amount.

I started working in the bank at 18, so any job is possible. I mean you have your grades so you can apply for anything within reason and work your way up the ranks. Just depends on what you want to do and what industry you want to work in.

Interested to see everyones opinions too, im currently looking for a job for the next few months while summer holidays are here but they all seem to want 3 years of experience in industry and i have 0

Retail , but it all depends on what you would like to do. What are your interests/ wanted to do ?

My little sister is 18 and she works for a chip shop

Locally owned, not a chain

If you can manage to find a locally owned business, they're usually more generous with their wages and are more understanding when it comes to time off/occasional late comings

vs

A chain store like Tesco or Morrisons who will throw the book at you whenever they can

You should look for a job that you think but suits you. Even if that means you have to go through the extra education for it