Roundup would be better than tilling: it sprouts from the bits that tilling leaves behind.

Get it growing REALLY well and 3-4 inches high - don't mow, pull or cut it back at all. Then spray it with Roundup (diluted according to the package directions), leave it 24-48 hours for the Roundup to hit the roots, then mow it really short. Give it a couple of weeks, and respray what's left and what is resprouting.

You will have to patrol with a hand sprayer to get the stragglers. , but that will knock it back.

To protect the shrubs and flowers, cover them in newspaper, or sit paper bacs on them while you spray. I use a cardboard shield between the spray and larger plants.

Ive had my front lawn removed by a bobcat. there is still Kikuyuy and cooch runners under the ground.....Ive just finnished digging it all up but there's still plenty there! can i use a pre-emergent herbicide (Simazine) to kill the runners as it grows through the ground? and will this kill the new lawn/Turf im about to lay over the top?