No. In the majority of cases a consultant is not necessary. Thus grants for export, training, consultancy and most other services may be applied for quickly and easily without assistance. However, in the case of grants for capital investment and research & development the application procedures are complex, and, more importantly, the rules applied by the issuing bodies are not transparent.
In any UK project you will invariably need to demonstrate "additionality", "viability" and "efficiency" whereby only viability has its own normal English or business meaning. In the case of research and development further criteria must usually be met such as demonstrating "pre-competitive" research, "collaboration", "market failure" or similar features. European Union grants will normally require demonstration of the European socio-economic benefit, exploitation routes and/or conformity with EU directives.
The critical factor, however, is that most grants for research and development and some capital grants are issued on a competitive or challenge basis, thus only the very best will succeed in winning awards. Consultants will not only be familiar with the hidden rules but will be able to complete application forms quickly and efficiently. Most importantly they can ensure that all of the key points and critical matters are covered to the applicant's best advantage.