I would take it to ATS, they will make sure the nail is in a "safe" position and repair it. A repair will cost around a tenner.
As mentioned above, if its close to the sidewall it will need replaced.
Had a screw in the tread of my tyre for the last 2 weeks. It wasn't holding air for more than a week so got it mushroomed for a tenner ( last time I had a shroom it was a fiver but that was 7 years ago ). Phoned around and most places wanted £15.
Get it done m8. Though it's not likely to blow out it is a possibility.