There is a proverb about giving a man a fish and feeding him for a day or teaching him to fish and feeding him for life.
Engaging a consultant to help write a single tender is a short-term fix which may be effective. It is usually quite expensive.
Effective training, which is tailored to the needs of the individual and the company, equips people with the skills and confidence they need to write winning tenders. The cost is usually less than £200 per person per day.