I've been trying unsuccesfully to find a recipie using extract and grain steep for a Tennents style clone. Can't buy the stuff in AU anymore and I've been missing it.
I put that on the same level as Carling Black Label, vile stuff but if it is what you like then fair enough.
It is quite difficult to brew a quality lager using just extract and steeping some grains. I would think the only grain you would want to steep is carapils and that leaves a bit of residual body. Couple that with the extract and you wont get a low enough finishing gravity. Perhaps try extract and even a small mini mash of 1kg of pils malt. I would be guessing at what hops they use and yeast wise perhaps its 34/70 but from what I hear the S189 is a great yeast so perhaps you could try that.
Hopefully one of the extract brewers here may be able to come up with something better.