In principle, as long as you make your meaning reasonably clear, details of grammar, punctuation and spelling oughtn’t to matter to how the tribunal sees your case.
But things are not always as they ought to be. If you’re an adviser or representative, some employment judges and/or tribunal members will think the less of you if you get these things wrong, and that can affect the attention they pay to what you say. Let’s not get into an argument about whether ‘wrong’ has any real meaning here: it has a meaning in the heads of some at least of the people who may be making decisions about your case. That’s real enough to matter. It probably mostly boils down to snobbery, in fact.
(If you’re a claimant rather than a claimant’s representative, this post isn’t really for you: tribunals will be much more tolerant of what they see as mistakes, because you’re not holding yourself as any kind of an expert.)
So here are a few common errors to avoid.
The infinitive is the form of the verb that goes ‘to go,’ ‘to do,’ ‘to litigate’ etc. The sin in question is putting anything at all between the ‘to’ and the main bit of the verb; as in ‘to boldly go.’ There are scholarly arguments to be had about whether this is really an error in English or not, but quite a lot of people have been taught that it is.
The singular is ‘criterion.’ Not many people know that – but those who do tend to care disproportionately. So if you speak of ‘a criteria’ you may mean either ‘a set of criteria’ or ‘a criterion.’ ‘A criteria’ is like ‘a mice’ or ‘a children.’ One criterion; several criteria. (Some will also wince at ‘data’ used as a singular, though I don’t think I’ve ever heard anyone say ‘datum’ meaning a single piece of information. As for hoi polloi – just don’t go there: you’ll annoy someone however you use the expression.)
Practise is the verb, practice is the noun. So for example, a lawyer may practise as a member of a practice.
Apostrophes are notorious, but if you stick to these four rules you’ll mostly be ok:
the judge’s wigs’ fleas’ legs: one judge, two or more wigs, many fleas (well – more than one anyway); and 6n legs, where n is the number of fleas.