British guy with a job offer. What is next?

Okay so I'm from the UK and there is a company in China that has offered me a job.
What is the next stage? Do I actually have to go to China first? Maybe I'm reading things wrong but it sounds like I have to go there first . . . then fly back to the UK then fly back to China which seems a weird way of doing it?
Can the company apply for their Foreigner Employment Permit without me and just with my passports photocopy etc?
Sorry if that sounds dumb but I've read conflicting things online (maybe people who are already in China confusing things). I'm going to assume they can get the ball rolling without me flying there first though and then I just apply for the Z visa in London? . . . then fly out and do the rest of the permit related activities?

Also are their any specific requirements and how do I go about finding them? I know for my employment visa in India there was a minimum salary etc. I have a the relevant qualifications and the work experience but just wondering if there are any hidden things I should be aware of? The company is Chinese and have never employed a foreigner before so we will be helping each other through the process.

For the record I have previously lived in china for 2-3 years as an intern between degrees but them visas where a whole other routine compared to this!

Thanks in advance for helping me out!

Tin-Tin