If MN1 Not Granted On Time Then What Other Options???

Dear All

Me & Mrs are granted ILR recently, I have already applied for Registration as British Citizens on MN1 form for my two UK born children. Once we receive the certificates we are planning to apply for British passports (one week service). We are waiting & recently spoke to the team who deals with MN1 applications, they are saying it will take up to 6 months to process the applications. We have a planned abroad visit in January 2015.

My questions are
1. If my children are not granted registrations certificates by December 2014 OR if there comes any problems with already submitted MN1 applications & they take more time for whatever reason, Is there any other kind of visa which we can apply over the counter for my children which lets them back in UK after visit abroad. Because we don't want to miss this planned visit abroad.

Children can apply for settlement, as children of settled person, but that will cost a lot .

I believe the Registration may arrive before the planned holiday.