The A+ Certificate is a recognised course and will add some value. If you have the time to study and can afford the £130 for the exams then you have nothing to loose by doing this.
Don't however expect it to open endless doors. Have a flick through the local job paper and see how many jobs asks for this kind of qualification/experience and I doubt it will be many. That alone shouldn't put you off doing it - just go in with the realistic expectations of what it will acheive for you.