I think the Gatekeeping hearing will purely deal with the Cafcass report and decide what happens next, which should be an FHDRA - ie a date for first hearing. No evidence will be allowed until final hearing. When your solicitor says prepare a statement for the next hearing, do they mean a position statement? I would be asking for an interim order at FHDRA to ensure you get the time you currently have until final hearing.
I started a new thread on the new "triage" system after getting some info from a legal person on Twitter! Having noticed that people are getting gatekeeping hearings. It is actually delaying the time before first hearing. I can see why they are doing it. In cases where there are allegations, the gatekeeping hearing decides whether it should go to a fact find first or directly to a first hearing. This is not good in my view. In your case it should be fine as Cafcass have said no welfare issues. But if Cafcass report that the Mother is making allegations then the gatekeeping hearing might decide to order a fact find hearing or a section 7 before it even gets to a first hearing. Even some Judges are frowning upon that. Because the gatkeeping hearings are not being done by Judges but by Legal Advisers - who aren't Judges or Magistrates. Whereas when a case automatically went to a first hearing, a Judge could dismiss allegations by looking at the history.
The problem is the courts are overloaded and underfunded. In your case though the gatekeeping hearing should just decide the next hearing is an FHDRA and you'll get a date. But the delays are very frustrating.