It is difficult to advise without knowing about your circumstances. For example, is your line of work likely to require you to use word processing as part of the job? Do you take work between home and office that involves word processing? Etc.
MS Office seems to be pretty much the industry standard in the UK. Look at the job ads and you will see Word and Excel quoted commonly as essential or desirable experience, as well as specialist software such as Sage. So, if you are looking for a job, or likely to be looking in the near future, it might help to get MS Office.
Sorry to be so vague - just trying to look at the bigger picture.