Couple points. No intermediate piers required..
Static has good point ref expansion joints, personally would not worry, You are only 14 metre long with no hard end restraints just two end piers. If she is going to expand she has enough flexibility to go both ways and as you say you are working on an arc, so she can go out that way as well.
You don’t say what radius you are working curve to. Hope you have got enough depth for radius peg to work your arc from. Both bricklayer and ground worker will need it to set out from.
Price. Notice you are from Herts. Used to be a lot of good greedy bricklayers round the Stevenage and Garden City area.
I think that possibly the rates here are higher than what noseall would expect to pay up in his neck of the woods.
You are working on an arc, therefore can not pull a line. Sixteen course at least, lay four bricks, level four bricks, plumb min twice every four bricks, sixteen times every course, and that’s just the front. Going to be very very slow. Throw another problem in, what is your arc going to be, loose or tight. If it is tight affects your bond in relation to your perps. Could slow it down even further.
Can not work out how many brick you want as do not know whether the 14m is on the straight or round the arc.
I would budget for a decent 1&1 400 brick a day, but the hoddy would be scratching his back side half a day as he would have nothing to do.
Cheapest way out for you find a good single bricklayer who wants some week end work and labour on him yourself.. Hope helps.
old un