Quite possible. Your name may match a screening list issued by another authority. That authority has no obligation to notify the embassy. Normally that match is then verified against personal ID and then released or confirmed. In addition, any transport company can have their own blacklist.
your congressman won’t be able to do anything. Just go online and book an appointment for notarial services. Take your passport and when you get there just tell them you want a notarised copy. They don’t care what it’s for.
After transport , import fees and whatever fees the British government imposes to certify it you will have spent enough to buy a decent used car in Britain