@Saras: The first question that you need to ask yourself is where is your personal statement going to be sent to. Is it a native English speaking place or not.
Now, using certain phrases like "it would get me closer towards my desired career" should not be a problem. However, when you explicitly talk about idioms, in general sense, they should be avoided. However, this does not end there. The usage of idioms in writing a personal statement has also got to do with the exact idiom that you are using. A personal statement is, in a way, a reflection of yourself. You may use an idiom or two over the statement but be careful not to use any idiom or phrase that may be difficult to be understood by the reader.
Avoid over usage of phrases or expressions. That conveys the idea that you do not really have a clear idea of what you want to say. At the same time you do not need to sit down with a book on idioms to decide which one goes in and which one does not. Try and keep it free flowing. That, in general, should be the way to decide if the idiom/phrase you are using should be there or not. Avoid euphemism.
At the same time, keep in mind, in formal English idioms are usually (not always) avoided. At the end of the day, it also depends on the examiner who reads your statement. Some people are too picky about it and have a strict 'NO' policy for idioms while other people are more liberal about it.
Hope this helps.