One other thing to consider is the processing time for a US visa. They recommend starting the application process at least 10 months before you want to move back (and November is only 8 months away).
Also, if you want to apply using DCF filing, you, the US citizen, need to be a legal resident in the U.K., either holding a spousal visa, FLR(M) or ILR... and so if you left in July and re-entered as a visitor, you would no longer be eligible to use DCF filing for his US visa... which means you would have to move back to the US to apply for his visa.
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