I'm very frustrated at work due to crap management, no support and appreciation and there is no way to progress. However, I have good flexibility and I do like the job itself.
But there's a job advert for a great looking job which pays £4K more and has better benefits, and looks like it would offer progression. But the closing date is tonight!
Would you apply if you were me? I'm worried about applying, then deciding I don't want to leave my job, but my current job finding out I'm looking for another job somehow (for example, if someone in the new company knows and tells someone in my current company, as both are local) 
Would you just apply and see what happens?