I wanted to provide an update to my own post.
I found it very difficult to find any useful information in regards to doing a refinance on a US property while living in the UK before I started the process. While clearly my experience only applies to my specific refinance, I feel there may be some useful bits for anyone finding this post in the future while investigating their options.
After contacting several lenders and mortgage brokers I found multiple places that were willing to work with me knowing that I lived abroad. In the end the one offering the best rate also had good reviews elsewhere online (I'm not going to name them in the post, but will happily share the details by PM if anyone wishes).
I was able to complete the entire process without travelling to America, though I did have to visit the US Embassy to sign the closing documents.
All of the initial disclosure documents were either signed electronically, or provided to me as PDF files for me to print, sign, rescan in, and email back.
For the final closing documents I had to sign them in front of the Notary Public at the US Embassy. This was at a cost of $50 per Notary seal and I had to have 9 of them on my closing documents, so a total of $450. My mortgage broker was willing to reimburse me for half of the cost of this, but I doubt that is standard.
While I was aware that the Embassy charged $50 per Notary seal at the start of the process, I wasn't aware that so many would be required on the closing documents.
After signing the documents, I scanned in the signed and notarised pages and e-mailed those back to my mortgage broker the same afternoon that I signed. They also provided me with prepaid UPS label to send the physical copies.
The entire process was mostly smooth, though the time difference between London and California (where the broker was based) did cause a few delays throughout the process. I did a 'streamline refinance' and was able to complete the entire refinance is less than 5 weeks.
An option that I hadn't considered until near the end of the process, is that you could do a Notarized 'Limited Power of Attorney' letter at the US Embassy for $50 if there is someone in the US that you trust enough to see through the signing of the closing documents.
Again, this is my experience with my situation, but hopefully others may it useful. I'm also willing to answer any questions that anyone may have.
