I have done all the preliminary stuff, my staging date isn't for a while yet but also decided to go with the government nest scheme as it's free and easy to transport if staff change jobs etc. My accountant has said he has all the letters I need to send out ready for when my staging date comes up. I did consider the NHf one but my accountant does all my payroll so I wanted one that he would be familiar with too and he said the nest one was a good option.
They all should operate a similar way.
The company doesnt actually "do the pension" they look at the market and put the money in one that they think is the best, if it's not performing well they move it after the allotted time.