Yes you need to do a tax return theoretically. And yes you need to do a partnership tax return. I'm not sure about the reference to Limited Companies because you weren't one and if you had been it would be a Corproation tax Return and not a Partnership Return. As the name suggests, the Partnership Return is specifically for partnerships.
No, as Tom says, it isn't possible to one before the end of the tax year. The revenue may even change the format of the form between now and then.
If there's a profit to declare in the period (though I guess there wasn't going by what you say) then there absolutely MUST be a tax return declared.
If there was a loss, and you want to take advantage of any tax losses elsewhere (such as against earned income) then you need to do a tax return too. If however there's no great benefit to you in that the Revenue would probably be prepared to accept a no gain / no loss position if it's perfectly clear the business fialed and you lost money. You'd still have to physically submit a tax return but it could be done basically as a NIL return and justified if selected for enquiry.