I am not certain of current rates but £10/m seems a good starting point.
If you can't work out a rate, then price it on how long you will be there, and it its going to take you say, 5 days, then you want 5 days money.
Obviously, hardish joints, bricks that chip easy, the joint finish will all determine how hard the job is.
Scaffold is extra, as is materials and disks. But you may have to compromise - without working for nothing though
Also, don't forget that changing perished/chipped/cracked bricks is also chargeable.
What you can offer that the other guy can't may be the selling point, so make sure to stress the benefits
And check the gutters and fascias while you are there, and anything else that may need doing.