Tax return question

Hi all,

From about March this year I had two jobs a full time 9-5 5 days a week, and a weekend job. The full time job was listed as my "second" job just because I started it chronologically after the more casual job. As a result, I was taxed a flat 25% on my wages for the 4 months or so I was there.
I'm no longer working due to being back at university and so am in no danger of going over the £5,300 taxfree threshold or whatever it is. Therefore, to get back the tax I paid, will it be automatic at the end of the financial year, or is there anything I can do to get it back earlier? Or will I need to take action whatever?

Cheers!