I solved it, was looking through some of the old documents i had written and came across an old Retropie.txt file i created years ago which i had written myself an old guide on how to set up the network rom shares. In the fstab i had used the following.
//IP/Gaming/RetroPie /home/pi/RetroPie cifs username=pi,password=***********,uid=3001,gid=3001,nounix,noserverino,rw,user,exec 0 0
I had totally forgot that i just had to give the pi read/write access to the Gaming dataset and then in fstab i just needed to drop in the uid, gid and rw and it now saves.
Cheers