I am a citizen of the United Kingdom, I will be travelling back from a year in the USA through Brussels back to England. The flight I am considering buying has an hour layover, will an hour be enough for me to disembark, clear any passport/customs and get to my other flight on time?
Will I have to go through a full security check as well?
I am on one ticket, so I will already be checked in for all my flights.
If your connecting flights happen on the same ticket, you will be guaranteed to arrive at your destination.
A ticket is a contract that says "we will transport you from point A to point B". In such connections, the delay is always calculated to allow you to easily change planes. If the inbound flight happens to be late, the airline will arrange the connection so that you can reach your destination, either by helping you transferring quicker or putting you on a later flight at no charge for you.
A story thet happened to me: I had to transfer at Atlanta coming from Paris. The transatlantic Air France flight was late. By the time we took to clear immigration and customs (the line was long), find our terminal and reach the gate, our connecting plane was already gone! I contacted the Delta Customer Care in the terminal; they promptly rebooked me on the next flight. This case has worked with two different airlines (Air France and Delta) as I had a through ticket.
An hour should be enough to make the transfer, even if you'll have to go from one terminal to another. Which airline are you travelling with?
You'll have to pass security check/border control again depending on where you'll land (depends on your airline as well)
