Got a letter from t'council asking for some details about council tax. No stamped addressed envelope in there with it - and I can't fill in the details online or over the phone - cheeky pricks!

However I have an SAE from another council department, but the address is totally different. If I scrub the address out and put this one on will it get there? Or will royal mail think "nah fuck this guy trying to charge the wrong council department for his postage" and chuck it in a hole?