Your experience sounds a bit disturbing, lilybelle.
DH thinks I should continue to pay for Medicare and health insurance in US and come back at 6 month intervals to get things checked. I really don't want the expense nor do I like the idea of jumping on a plane twice a year. Maybe the other suggestions will work out.
Oh, gosh, maybe make a plan where you budget out the money for a year, for peace of mind, and then see if you can make it work? At the very least, you could Google around for a list of private specialist in your-area(s)-of-concern to at least get an idea of what is available. You could also budget that money to pay for BUPA or some other private healthcare in the UK, instead of continuing US coverage.
I know we have all had different experiences with the NHS, but I really do think it will be easier if you come over thinking "how can I make this work" instead of "what will probably go wrong". We can all give you anecdotes, but it really will be down to how you respond to the particular situation you find yourself in.
I am a very (probably overly) informed patient--my mom works at a world class research hospital in the US and is slightly paranoid/loves getting tested for things. My medical history is detailed and HUGE, and I haven't really had any issues discussing it with my GP or the nurses at the practice. I came over just after discovering I was low in vitamin D and that my dad has serious issues with vitamin absorption; all of my concerns were taken extremely seriously and I'm getting the treatment I need (and being monitored in case anything changes). I suppose if I'd just come in a demanded a test for vitamin D w/o any reasoning behind it, it would have been different, but it doesn't sound to me like you will do that.
Prepare the best you can, and then do the best you can once you get here. And always stop by when you need to figure something out or have a rant! (I, for example, have had the occasional (massive) whinge about the receptionists at my practice; they seem mad. at the world.)