Some people are very adept at representing themselves. The main issues are if the ex has legal aid funding for a solicitor and barrister. A solicitor for an ex will pull every trick in the book against a litigant in person, and commonly this can lead to delay after delay. Their goal is that you will give up and go away and the longer it takes, the more entrenched the position becomes that the children have been living with the Mother without issue for a long time. If and when you do reach a final order, it will need progression from a minimal amount of time.
Some of how well you do might depend on what sort of person your ex is. Is she the type to make allegations of abuse? If so she'll get legal aid funded lawyers (whether the abuse is true or not) and there will almost certainly be a Section 7 report (which takes a few months).
The advantages of using a barrister are - if both sides have lawyers then they are expected to negotiate at hearings (the hour before a hearing) and can sometimes thrash out an agreement for a consent order so it goes no further. If no agreement is reached, a good barrister can argue back against the Ex's solicitor and maybe even get interim time ordered at the first hearing.
So what is your situation? How long have you been separated? Do you get any time with your children at the moment? If your case is simpler - neither of you represented and no allegations, then representing yourself, if you're a confident person, could be a reasonable option. The key to that is to always sound calm and respectful and don't criticise the Mother - keep it child focused.
From what I've seen, people who use a barrister tend to get better results in less time. But it depends on the circumstances as some have achieved results on their own (although it usually takes longer).
