So here's a little more detail of how we got here....
I do want to stress though that the wording in an email we recieved from HO was that his application didn't even begin to process until biometrics were complete. SO, it seems that the 6 month "clock" doesn't even start until biometrics are done. Another thing to point out in our case is that we have a permanent address here in the UK with my husband's parents, making correspondence and proof of address much easier. If you don't have someone to live with then the most feasible thing would be to let a holiday cottage and do the process that way. We are very lucky that they processed his application in the time they did, and I would dare say it was helped along by our gentle nudging and giving them our timeline for being in the country.
Something else to mention, hubby was talking with passport advice about a month or so ago and he went through his history with the agent and was told that he was in fact eligible from the start for a British passport, per the 1948 Immigration Act that states that if his mother was born after 1948 that he immediately was eligible for a British passport because he inherited citizenship from her at birth. Hubby asked about the UKM process (without stating that he was actually in that process) and he stated that there was no need for him to do that because his mum was born after 1948 and that UKM was only for mothers who were born before 1948 or who had other extraneous circumstances. While the passport wasn't meant to be an indication of full british citizenship, that it sufficed for all things such as NI, NHS and residency. He told him that he could simply apply for a passport and if he wished to get a letter showing his citizenship, that he only had to request that letter from the HO stating that he was a british citizen by descent. As of right now we have applied for the passport and they don't appear to have any contact with nationality so if my passport arrives before my ceremony, then we know that route was the easiest to take, if it comes after his ceremony then UKM was the way to go. I was placed on the phone with a supervisor in the same call to passport advice who confirmed and quoted the 1948 Act. He was reading line for line and gave me places to go and read the info for myself. It did appear that UKM was a bureaucratic waste of time and just more red tape to get through that wasn't necessary.
NOW...the passport office processed my application within a day but sent me another form due to me signing too close to the line, so I had to get new photos taken and my countersignatory to fill out his part again, but instead of my form being sent back to Liverpool, it was to be sent to Peterborough which is the only place in the country that prints passports. My understanding is that if I weren't entitled or I sent the application in error it would have already been refused by Liverpool and that any new forms requested of me would have been sent to Liverpool. The fact that my forms were sent on to Peterborough reflects that all should be well and I'll either have an interview or I'll simply have my passport show up.
Interestingly enough, what I did to be able to travel to the UK in the first place was to apply for another US passport as Home Office had my passport for the UKM process. Having a second passport (the first obviously canceled when I got the second), did not hinder my process at all.
If you plan on doing this route, I will stress to you to have bank statements showing you can support yourself, have proof of your job back in the states, have a return ticket printed out and do not do not do not bring American Cash as it is difficult to change unless you are willing to take a huge loss in conversion. Only stress that you are here for a holiday and are taking an extended leave of absence from your job (they asked us how that was possible for hubby to do and he is a police officer who worked private contracts so he was able to take off due to the flexibility of his job)
Don't mention any intention to move to the UK or to get your citizenship, they will automatically assume you are going to overstay.
If you are coming with children, you must be ready to answer questions about how they are going to get their schooling. We homeschooled so that was a non-issue for us, but the Immigration Officer stressed that we could NOT put the children into school or use NHS.
I would strongly recommend travel insurance for the duration of your stay so that you won't have an NHS bill hanging over your head while your paperwork is processing as that is grounds for refusal.
Any other questions?