Unhappy with my PhD program in my home country, thinking about applying to another university in UK
It happens that people change their PhD programs (I know a few.)

Basically what you lose is:


Time (usually you need to start from the scratch),
Relationship with advisor (the latter is not always the case).


If, for any reason, the first year was bad, it is rather unlikely that the next ones will be better (I have never met anyone who is enjoying PhD more and more with each year...). Moreover, if you don't like it, maybe your advisor does not like it either and eventually you won't be able to finish at all.

But beware - "grass is greener...". You can experience the same problems in other places. So here are the most important things:


What is not working?
Do you have any reasonable argument that in the target place such thing is better?


(Anyway - if you are very unhappy after one year (of 3-5 more years to come), then just change it to another PhD or to something different (don't disregard other careers). It's better to end up with "wasted" years or a "suboptimal" career than hanging on a tree.)

HOW to do that is a different question (or questions - because it involves both application to a new program and quitting your current one). See e.g.:


current PhD applicant applying to another university
Apply to PhD after expulsion from another
Switching from one area of graduate study to another?