You wont have any penalties as such - if you have not got this sorted within six months you will have to complete your first B1 - you will just have the hassle and costs of dissolving it. Also, you will have to obtain the usual - Revenue Clearance Letter(you may have to explain that you do not wish to tax register/or deregister if already registered), place newspaper ad, etc.
Did you form it yourself, or through a formation agent. If through a formation agent, they may "buy it back" which will mean they will have to change directors, change registered address, possibly change main objects, change shareholders. I've seen it happen this way sometimes.