I'm more familiar with that one than the one in swindon. It looks extremely terrifying from above, but what it actually looks like from the ground is a bit of a weird run of roundabouts one after another. If you take them one at a time rather than consider the intersection as a whole, it works fairly simply. It's actually shockingly intuitive.

Compared to the nearby roundabout onto the M40, which is of a much simpler design, but is covered in traffic lights, the Wycombe magic roundabout is actually much better at moving traffic around.