Ask HN: Tips for HR Systems

I am trying to do a favour to a colleague, but I am totally bewildered by the amount of HR systems on the market, and I guessed every growing company has some HR needs so thought I would ask here.

I have used BreathHR before but it gets expensive for 150 staff. They would like more granular permissions too. They are particularly interested in assistance with staff onboarding, delivering contracts, h&s documentation etc. They are 100% UK based. They can't self-host.