A general course teaches you to describe your bedroom and order in a restaurant. If you need the language for meetings, email and a client call on Thursday, almost none of that is the material you need — and the material you do need is much smaller.
Your working vocabulary is narrower than you think
Professional conversation runs on a few hundred terms: your industry’s nouns, a dozen verbs for agreeing, deferring, disagreeing politely and asking for clarification, and the phrases that manage a meeting. Collect them from your own work. Take a real email thread and a real meeting agenda, and build your list from those rather than from a textbook unit.
Prioritise being clear over being correct
In a work context the cost of a grammatical error is nearly zero and the cost of being misunderstood is high. Short, plain sentences beat elegant ones you might get wrong. Learn the phrases for repair above all: could you say that again, do you mean X, let me make sure I understood. These prevent the expensive failures.
Rehearse your actual recurring situations
You have the same five conversations every week: a status update, a question to a colleague, a disagreement, a request for more time, a call opening and closing. Script each one once, say it aloud until it is fluent, and you have covered most of your working week.
Reading and email first, if that is what you do most
Many jobs are mostly written. If yours is, written practice is not a compromise — it is the target. Speaking can follow. Being able to write a clear message and read an ambiguous one is often worth more professionally than being able to chat.
Aim at your own week rather than at a syllabus. Two hundred well-chosen terms and five rehearsed situations will get you working in the language long before a course would.