NigD, LAAS & WAAS are still vapor. Don't exist in the US. But the GPS approaches are still accurate. The only requirement for augmentation is for precision approaches, not non-precision. Even the fixed-wing folks are flying GPS approaches, & we're flying them to points-in-space in helicopters to 300/1 at heliports, & 200/.6NM offshore. I've never, ever been off course on a GPS approach if the CDI is centered, & at airports, with the needle centered, you're over the runway, close to centerline. GPS approaches are much more accurate than VOR, & about the same accuracy as localizers. Should be the same in the UK or anywhere else.