I am finding that if i park on a slope and put the car into Park, my car will roll forwards or back maybe 5-10cm after i release the foot break.

I have had my handbrake tightened and recently a transmission oil change but its still happening.

I have just ordered a new set of pads all round to see if this will help.

any suggestions????

 

The hand brake does not use the pads, it uses shoes inside the top hat section of the rear disks.
I'd say the rolling you get is pretty normal, but if you use the handbrake all the time you may want to check the shoes.