Thanks everyone.
I emailed our HR department and got them to send me on a copy of the Maternity Leave policy. And one line clearly states "(Name of Company omitted!!) pays full salary while on maternity leave, so social welfare contributions will be deducted at source".
I was just nervous that since the increase in maternity leave that they might amend their policy.. which I'm sure they are entitled to do! Anyway, it looks to be all sorted. I might mail the HR girl again today, to share my good news!!
Thanks for replies.