Your fucked m8,

I have sound deadened the party wall at mine and can still hear next door, it's a lot better but not gone.

I built a stud wall infront of the brick party wall.
I used 2" timber fixed to the wall, 50mm noise insulation quilt, then 2 layers of 15mm sound block plasterboard and skim.
I found out afterwards I should have built the wall free standing and used resilliant bars on the studs.

But you won't b able to get a good result without moving the rad and losing 3" off the wall.

You can buy stuff to dot n dab on but you need a minimum of 60mm clearance