travelling abroad just before ILR appointment?

This is probably a dumb question and forgive me if it's already been answered elsewhere, but we're planning a trip home to the US next summer July/August time. My 2-year spouse visa expires on 14 August.

I believe I have to call the Home Office for an ILR appointment around 18 July (eg 28 days before visa expires)? At the moment, I stupidly forgot about this and booked my holiday off from work for 23 July - 1 August. Will this be a problem?

It's right in the middle of those 28 days before my visa expires. Can you request your ILR appointment for a specific date, thus avoiding holidays? Can you even travel out of the country during this time? I need to confirm our holiday dates with work asap so any advice anyone has would be very much appreciated. 

are you going to apply for ILR in person or by post?

in person i requested my appt for a certain date as i travel alot for work. when i called within the 28 days they said they could take me the next day!!!!

The only thing that happened is when i entered back into the UK someone looked at my visa and said 'hey, you know this is about to expire?' and i said 'yup, i have my appt next week to get ILR'

that was it!

That answers my question then. I'm planning on going in person, so according to what Aimiloo said, we should be able to just request an appointment for when we get back from holiday. Thanks!