Thanks for your replies.
I'm running the E10 fuel in it (Ethanol). I've added Super premium (98) to the tank and will refuel with that next. I will get another mechanic to also look at it. I also checked the oil levels and made sure it was full (It was halfway between empty and maximum). The engine is at it's loudest until it warms up, but not so loud that you can hear it over the radio while driving.
I've recorded my engine, it sounds really loud and to be honest quite knackered. It sounds similar to the video that you posted as a reply above.
https://youtu.be/j39SNbW5Vys