Welcome.
I would have to say, avoid student loans for an undergraduate degree if at all possible. US student loans will follow you to the grave, for all intents.
No, seriously, you can't discharge them in bankruptcy, so unless you do a public service job
in the USA that would qualify for their forgiveness after ten years, you will be paying them back regardless of your finding work in your field or not finishing the program.
As you will be needing to go to grad school, that would mean even more expenses and loans, unless you can pay for it all out-of-pocket. I don't believe you will be eligible for any financial aid from the sources usually available to UK students either as an undergrad or a graduate student. You will also be classified as a foreign student, so plan on the tuition and fees being exponentially higher than paid by a "resident" student.
That said, going the student route as a trial-run for your relationship is an interesting option. Hopefully the experience of being in an unfamiliar education system won't cause you too much stress, as coming over to the UK from the USA is kind of stressful at the best of times. Going back to school with a bunch of "kids" (which is what the undergrads you encounter may seem like) is also a rather strange experience after being away from education for a decade.
Have you contacted the placement offices (for employment of graduates) at the Universities you're considering to discuss their placement rates for their graduates, especially in your field? Of to see if they offer any sort of assistance to their alums in finding their first paid professional jobs?
Also, have you checked out taking the bus instead of the train? Might be cheaper, as fares on Megabus can be bought at a discount in advance.
Best of luck!
[Edit: Also, in the last couple of weeks I heard on the news that the government is concerned about the lack of mental health professionals in the school systems. I believe I heard them say that there was to be a proposal to fund more training positions to get professionals into the field/schools. I can't tell you if that was the Scottish Government or the English Government, but it might be worth spending a little time running that information down. Not sure if it would apply to a foreign student anyway, or if they're going to just try to send more cash into the system to expand programs instead. Unfortunately, I only heard the news story in passing and wasn't paying a lot of attention to it.]