I'm kind of mixed opinion about the bikes, since 3 just die way too fast. I'd personally make groups of 6.
Also, I think you have too much tank killing stuff-since black knights can deal with tanks reasonably well, 8 meltas seem to be going overboard, especially considering the fack that your whole army can be tarpited really easy.2 heavy flamers on one 10AV vehicle just might not cut it.
Instead, I would, again, group them up to six, so they dont die as fast, and give sarge a power weapon.(especially considering the fact that if you are so close to get the melta bonus, you probably would be able tho charge anyway).
Also, termies can deal with vehicles pretty easy, since they dont scatter when
DS(just split fire
AC on back armor of the vehicle that needs killing)
Not a fan of the Command squad, but I lack experience in that regard, what I DO think you have way too many points in your
HQ and, honestly, not enough in
AA. Sure, you can jink away from 1 hellturkey, 2 are a problem.
I could carry on, but I feel it's better to wait for some feedback