As has been said, job is rough/note done correctly, despite this, it will work fine, which unfortunatly is what us proper, work proud, by the book, plumbers are up against 🙁
As mentioned above,
£300 all being told, is probably about right, if a little cheap for the job as a whole (done to a high standard!!) just be aware of the guarantee compliance....
It just needs clipping and lagging.
Nothing inherently wrong with the speedfit elbows being used, just makes for difficult lagging and a rough looking job. They are fit for purpose by definition. Pulled bends/tectite sprint would have been a better off the shelf option if your “plumber” couldn’t bend/pressfit.
On a separate note, Get some loft insulation?!
Stu