P35 return and Payroll Software

Hi

My business partner and I have just started up in practice and won our first client.  Our client registered as a limited company in November and was set up for payroll shortly after.  Unfortunately they never activated their HMRC PAYE online services so their account is not set up to accept the P35 return yet.  We registered for an HMRC agent code last week (very quickly after the client approached us to be their new accountants).  Given the timescales, we should be activated for online services by cob Monday (14th May) and it'll take another 4 days after that to register the client to our agency (which is really cutting it fine for the May 19th P35 deadline).  Has anyone got any suggestions of anything we can do to submit the return without waiting for all the systems to be set up?  It should be a very simple nil return, so shouldn't (i would imagine) take too long once set up, but we don't want to be cutting it so fine that we have no slack in case something goes wrong. 

Also - going forward I've suggested the client downloads some payroll software and have found a list of free services on the HMRC website.  It is a single employee company, so any of the below can be used.  Does anyone have any recommendations of which may be the best out of these:

12Pay Ltd (Opens new window)
IRIS (Opens new window)
Keytime Objective Ltd (Opens new window)
Payroo Ltd (Opens new window)
 

Thanks