Will broadband work without microfilter?

No. You will experience drop-outs (occasional drops in your connections). We asked a seasoned telecoms engineer this question: A microfilter is really to cut out the ringing current, so even if there's no phone on the line, if someone called the number if will cut off the ADSL (or Fibre) signal due to the ringing generation."

However, what people usually get confused over is whether they already have a micro-filter built into their wall socket. It's likely you do, especially if your socket has to holes- one is for your standard phone line, the other your ADSL or VDSL connection. These are known as "NTE5" faceplates. These 'faceplates' generally already contain filter your connection by splitting the ringing current from your broadband connection.