what size is the brake pipes at the rear as i was told in my advisory after mot that these will need replacing for next one can anyone help?

Really need to ascertain whether they mean metal pipes to rear which are best replaced with copper, or are they talking about the flexible hoses which connect the stationary metal pipes to the rear brake cylinders/calipers which of course move with the rear axle?

You can almost certainly buy made-up metal pipes with the correct new ends that will fit right in, and the same with flexible hoses.

Just don't be too confident any of them will willingly come undone. You may find the junctions of flex pipes to metal pipes have a death grip on each other and on the brackets holding them on to the chassis.

CharlesY