I did mine around 8 years ago, around 14m total. Semi, with just one straight forward run at the front and one at the rear. There were no soffits or fascias originally, just half round plastic guttering. Two of us, me plus grandson, mostly working from only one double extension ladder. Process was carried out using a rope, to support the far end of long sections and it took a long weekend to do.
Next door had cowboys in to do their joined to our gutters, shared fall pipes in the middle, new square botch joined to our half round, a right mess and leaking all down our walls and the gutter fall was all wrong. So it was forced on me to do it.
A couple of quotes from what might have been more botchers ranged from £900 to £1200 to do the job matched to next doors. I decided I could do a better job and I could buy all that was needed for £250. I fixed the fascias first, it just pins in place with stainless pins, then soffits, then finally gutter brackets and gutters. I calculated the correct fall for the gutters over the distance, then was able to use the fascia as a level reference, with an end to end string line for marking the gutter bracket positions.
The hardest part, was the constant up and down the one ladder, plus the moving it. I invested in a sliding mitre saw, before I began, which made it easy to cut fascias and many short bits of soffit perfectly square.
