Changing career is a gamble
Changing your career path can be a costly and difficult business, both in monetary terms and also in finding a company to give you a chance to prove your worth.
Applying for graduate roles at this stage, you will find yourself up against some tough competition. Graduates with a software engineering background and one year's placement experience may seem more desirable to a company that wants to train and develop their new recruits into the corporate mould.
Training courses are an excellent way to diversify your skills. However, Java has gone out of fashion over the past year. To say this market has seen its best days may be premature; companies that have invested in this technology will continue to require skilled professionals. The downturn in the market does not detract from the fact that Java is dependable and, for those implementing it, can be cost-effective due to its platform-independence.
A six-month apprenticeship does not guarantee a position at the end of it. It may therefore be a gamble financially and for your career. Only you can decide if this is a gamble worth taking. Be aware that six months out of employment on a full-time basis is a long time. You have spent three years in a support environment, but if you do have to fall back on these skills, remember that you will have to explain your reasons for wanting to re-skill in a different field, which may not endear your application to a potential employer.
An alternative may be to pursue a Java course on a part-time basis and look into getting a development role within your current organisation. If this is not feasible, perhaps look for a company that will want your current expertise in the short-term but will also offer the opportunity to move into a software-based role in the future.