If the Met Office confirmed it, then yeah, it actually happened - not just feeling like it. The data's there. What's tricky though is that when people say "hottest on record," they usually mean since records started being properly kept, which for the UK is roughly the 1800s depending on which metrics you're looking at. So it's genuinely extreme compared to the last couple centuries, but that's a different thing from saying it's the hottest it's ever been in geological time. Still matters loads for how we live day-to-day though.
The pattern you're noticing - where we keep smashing records - isn't random. We're not just getting one freak hot summer every few decades anymore. The baseline keeps shifting upward, so what would've been a rare event 20 years ago is becoming more regular. Whether next summer will be as bad depends on a bunch of things (ocean temperatures, atmospheric patterns, solar activity all play a role), but the general trend suggests we're more likely to see extreme heat events than we used to be. Some years will be worse than others, but you're probably not going back to the cooler summers people remember from the 90s.
One thing folks sometimes gloss over: "hottest summer" can mean different things. Some records track average temperature, some track peak temperatures, some weight it differently depending on which part of the season was hottest. Not that the Met Office is being dodgy - they're consistent in their methodology - but if you see someone cherry-picking a different measurement to claim something different, that's where people get confused about whether records are "really" being broken.