On the business show on RTE Radio 1 this morning, an entrepreneurial couple who have opened a sports shop somewhere in the midlands (and are being mentored by Louis Copeland) mentioned that the wife is going back to work now that her maternity leave is up in the same breath as explaining how much work she had been putting into her own business.
Just to close this off, I spoke to Welfare today and yes I'm entitled to work while on additional unpaid leave but not allowed while I'm on paid maternity leave.
You should check your contract of employment too. You're still officially an "employee" of your company and, if the contract has an exclusivity clause, your employer may have an issue with you working during maternity leave. This would be separate to SW's attitude towards it...