Building insurance FOR LEASHOLD PROPERTY?

I've bought small 1 bed flat in eltham.Our brooket told as that we Must have mortgage life insurance as this is obligatory,so we sigh for it.Then RBS called us to say thay we need to have builiding insurance.We called our brooker but he said is not true as our flat is a leashold and building insurance is included in service charge we are paying.What is correct?What is obligatory?My finacial advisor in Barclays said mortgage insurance is NOT OBLIGATORY.Are we being mislead by our brooker?( we are not naitive british)?