Moving from UK to California?

Hi, I am going to give some background information but it's not completely relevant, skip down to the final paragraph for the question.

I am a 26 year old male from England. I am university educated and am currently working as an Optometrist earning £60,000 a year and have saved around £100,000.

My parents recently moved to Australia and I am the only family member still living in the UK. I have a lot of friends but a lot are moving away in the foreseeable future.

I have always wanted to move to Los Angeles and have been looking at a place called Santa Clarita - just outside the city - and have been researching jobs. There are quite a few, but they don't match my pay, but with the money I have I could buy a condo with a small mortgage and live comfortably on that salary of around $80,000 a year ($10,000 less than what I am earning).

Short Question:

Anyway, what are the living expenses per year (not including rent) and are there many Brit expats living in L.A? Also, what are the steps of becoming a citenzen of the USA?

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