Yes, the 030 is like a souped-up 020 which the A1200 has already, so it's probably a good bet for compatibility purposes, and heat in a standard A1200 case will be an issue with an 040. However, an 030 is just as lame as an 040 if you don't have any fast RAM to go with it. Good news is that, while the 3000 and 4000 have some accelerators available without RAM sockets, I think every accelerator for the A1200 had either fast RAM sockets or at least some permanently fixed fast RAM, so it shouldn't be an issue.
Bear in mind as well though, that the FPU is external to the 030, like the 020, and some accelerators don't have one as standard. Probably not a big deal, but software that needs an FPU will crash if one isn't included.
