It's very simple: yield to people making a left from Shrivensham, then enter the first roundabout. The internal circle is not a roundabout, people already inside will yield to you. So you can continue going forward (over the KEEP CLEAR area) and navigate around the center anti-clockwise. You yield again to people from Shrivensham and depending on what exist you want you need to traverse another one or two roundabouts and exit the desired road.

That about rounds it up, I would say!