If they get Skylon up and flying, they'll have a horrendously complex, expensive, and fragile launch vehicle which is utterly unscalable and inflexible in the range of orbits it can target. More likely, it'll never get up and flying, but suffer the fate of every other super duper spaceplane project, turning into nothing but a big money sink.
The horizontal takeoff and "looks like a plane" aspect is cargo cult engineering based on what looks cool in sci-fi and what works for aircraft performing an entirely different task. Air breathing buys you next to nothing in the end, and costs a great deal. Liquid hydrogen is a pain to use, it's hazardous and it's awkwardly low-density. Carrying extra liquid hydrogen for cooling and a bunch of extra air-breathing equipment and aerodynamic structures in order to use atmospheric oxygen diluted 4:1 with nitrogen which must be dragged up to the speed of the vehicle before being used, all to avoid carrying a bit of liquid oxygen, is not the path to cheap spaceflight.
You can make a reusable vehicle without using exotic propellants, without carrying wings and landing gear to orbit, without any of the Skylon's other magic technologies. SpaceX is a lot closer to doing this than Skylon is to even having a working engine.