Well it is a myth that you need to be expert in .net to know BizTalk, not quite right.
You just need to know the basics of .Net which may take around 20 hours.
Even if you don't know .Net you can start BizTalk.
Only when you have to learn custom component (and few more topics) you should know .Net.
So well then start BizTalk but start good, Start right.
Find good reference there are only 3 good books for the BizTalk. follow just any one. Recipe BizTalk should be good starting point (just to start) then if you find interest in integration continue further.