AstroAlex26

Hi guys, still a complete beginner but whilst it's been cloudy all year pretty much I've been getting my kit ready for when the clouds disappear. I currently own an astro modified canon 600d, a skywatcher tripod with a skywatcher star adventurer 2i pro. I'm buying the skywatcher evostar 72ed soon and will be pairing it with the OVL field flattener. My question is, is the field flattener the only accessory I need to be able to use/achieve focus with the Sky-Watcher 72ed? Getting confused with conflicting advice found online and I'd really like a definitive answer before paying out for something so expensive. Thanks guys and clear skies