My chief worry is that if there are any post-op complications, I can't easily revisit the clinic to have them seen to. I read in a forum somewhere an exchange between Dr Feller & an unhappy patient. Dr Feller said that the patient needed to return to the clinic, so that he could conduct a proper examination. The patient complained that this was impractical as he lived on the other side of the Atlantic.
It is great that you are looking at other aspects of the process and being conscious of potential follow ups or touch up if that may be necessary. All such things should be factored into a patients decision and thought process as there is no clinic that can guarantee with 100% certainty, as is the nature of hair restoration.
You have received some great advice in this thread that offers real value.
As a patient myself, I travelled from the UK to Canada for my first surgery. We are all budget conscious to some degree or another, which whilst should never be the driving factor, being honest and transparent, of course it has its place and is an influence.
Once there is an honest idea of a feasible budget and if that budget is a genuine budget to find a quality surgeon, then I believe it is important to find the best doctor whose work you appreciate and has a reputation for consistently excellent results.
In doing so, you are mitigating the potential need for any revisit to the clinic. Sure you can stay "more local" incase that yield isn't as expected, but by staying "more local", for most of us that would mean a lesser quality surgery and therefore increase the possibility of needing to return for a touch up or having any issues which is also counter intuitive.
This would mean the touch up may again not be at the quality desired.
This is not to say that you do not have options within the UK. Other doctors worth contacting have been cited, but compare their cases and approach with your own status and objectives and an in person consultation prior to committing is always worth the inconvenience.
The need for a touch up with a quality surgeon is uncommon, and even more important to that effect is that you have the knowledge that the doctor will take care of you in the rare situation that growth isn't as expected.