There are two quite separate questions here. You may want to know what it will cost you to get legal representation for your hearing. In that case, you should probably start by reading Getting Advice.
The other reason why it is good to know a bit about the scale of legal costs involved is that this information is relevant to your former employer’s calculations about whether they should fight the case or try to settle it. Understanding something about what they are likely to be spending – and when – will help you make rational decisions about negotiations.
Legal advice and representation is not cheap. Costs can vary widely, so don’t rely on the figures given here as anything but a very rough guide.
Solicitors almost always charge by the hour. Few employment specialists will charge less than £80 or £100 per hour; some will charge as much as £200 or £300 – or even more. In general, more junior lawyers will charge less than their more experienced colleagues; and the larger and more prestigious firms will charge more than smaller, less well-known establishments. As a rule, when both sides are paying for their representation, the chances are that the employer will be paying more than the employee. (This is partly because it is quite difficult for non-lawyers to make well-informed judgements about how good lawyers are: the result is that those who can afford more often pay more on the basis of an assumption that the better lawyers charge more.)
Barristers usually charge by the hour for advisory work, and similar considerations apply: a Silk will charge a lot more than a junior barrister a couple of years out of Bar School. Hourly rates for barristers are generally a bit lower than for solicitors of comparable experience, because barristers’ overheads are lower. But barristers are normally only instructed by solicitors, so in general where there is a barrister involved, there will be a solicitor as well.
Hearings are traditionally priced by barristers on the basis of a ‘brief fee’ plus daily ‘refreshers.’ The brief fee is what their preparation for the hearing will cost (that is, the work they will do getting to know the hearing bundle, researching the law, preparing cross-examination etc.), and includes a fee for the first hearing day; a refresher is incurred for each day that the hearing continues after the first. A brief fee for a 5 day hearing might be anything between £2,000 and £15,000 depending on the complexity of the case and the seniority of the barrister; daily refreshers might be as little as £500 or as much as £3,000. Those numbers would give barrister’s fees for the whole hearing of between £5,000 and £23,000. If a solicitor is present throughout, add their hourly rate for 7 or 8 hours a day: maybe a further £5,000 or £10,000.
The brief fee is traditionally incurred when the papers are delivered to the barrister. How long that is before the hearing will depend on how much preparation the barrister is going to need to do: a very rough rule of thumb is one day of preparation per two hearing days. So if your case is listed for two weeks, your employer will probably incur their brief fee about a week before the hearing begins. It is important to know this, because once they have committed to paying their barrister a brief fee of – say – £15,000, that’s £15,000 they won’t be able to spend on settling your claim. This means that if you receive an offer of settlement to expire a few days (or in a longer case a week or two) before the hearing begins, there is probably good reason for the deadline: this is the point at which they will incur their barrister’s brief fee, and the pot of money available to settle your claim will shrink sharply.