It's helpful to know a bit about TG: They are a lot like Saurus. The main differences are they have one more WS, halberds (so effectively S5), stubborn with slann, and light armor (I know there's other stuff, but that's the big part). Since halberds cannot be used with shields, the light armor gives them the same armor save as a saurus. They also cost 4 points more.
I honestly can't think of too many times I lost against combat to a unit of TG, and I played a 2500 point game once a week from May to Aug (using 8th edition right when the book came out). Working out the math, your GG hit on 3+ (with burrows), wound on 2+ (with GW), negate armor (giving you a little higher than 50% chance to kill/attack), compared to them hitting on 3+, wounding on 3+, negating armor and dealing with a 4+ regen save (giving them 22% kill/attack). That puts the odds in your favor. The number of attacks should be about the same since you'll be running horde formation, something I don't think he'll do.
Assuming all life spells that aid combat go off (except throne of vines), the only changes would be that you now wound on a 4+ due to extra toughness and they have a 5+ regen save (22%). That makes the battle about even, but then add in your combat lord and everything should still swing in your direction.
Unless I'm forgetting something, your GG should be good against TG. I don't know why they would beat you without much of a challenge in CC. If you get lucky and he has a bad magic phase, you could really cream through a lot of them. The damaging spells are pretty weak (esp against your regen) except for the ultimate spell which he can't cast at you while you're in CC.
Good luck!