Whilst the official policy is that Accenture do not provide funding for CIMA, if you could provide a business case as to the need for one, and have the right level of sponsorship from above, then it is possible. The F&EP Practice within ACN does value a CIMA qualification, but usually will not be inclined to put many people through this.
As for where you will be placed within Accenture it will largely depend on the types of projects you work on for the first few years. That said even that is no guarantee as to where you will be placed. Once you join you can look to network with those in the area you wish to specialize, and this can be used as supporting evidence as to where you will be "housed".
As for whether it will be valuable in your career, kind of depends on what you want to do..