Court application (C100) I believe is £400. As for the rest, it depends on your appetite.
What is quite common on this forum is to self represent for the first few hearings (and use this forum as a resource) but spend on a direct access barrister for the final hearing. It may be that if the Cafcass report is clear cut, then there is no point in spending on an expensive direct access barrister; as quite often, once Cafcass have made their recommendations, the outcome is pretty much set. The family courts are set up to enable you to self represent as money should not be a barrier to getting access.
This way, if agreement is made early, it only costs you £400. Costs will be a lot more if allegations are made, as you may want legal representation earlier in the process as these can be more of a minefield.
Direct access barristers can cost between £2k and £8k for a 1 day final hearing. You do hear of people spending £100k on trying to get access, but quite often that is the solicitors filling up their days with billable hours and creating fuel for the fire.