The required corporate relationship between the US and UK companies needs to exist but assuming that it does, then an L-1 transferee visa might be an option - although USCIS (if the US company isn't a "blanket" approved company) can be really tough on L-1s so the outcome isn't necessarily guaranteed.
The good news is that the L1 visa is a fantastic visa. It's dual-intent meaning you can apply for greencard (as opposed to TN). Also your spouse can work! That is huge.
To be clear, one can proceed with a GC application even if in TN (or another non-dual intent) status. Such a filing however compromises travel (in the short term) and can impact the ability to renew the TN in the future if the GC application fails.
