Fascias, soffits, bargeboards, gutters and downpipes replaced in uPVC, or cleared, resealed and re-run where replacement is not needed. The roofline is the cheapest part of the roof to sort and the most expensive to ignore, because rotten fascia and overflowing gutters take the rafter feet and the brickwork with them.

Old timber fascia and soffit off, rafter feet checked, new board fitted and the gutter re-hung to a proper fall.
Blocked gutters cleared, leaking joints resealed or replaced, and the fall checked so water actually reaches the downpipe.
Downpipes re-run, brackets refixed and gullies checked, because a downpipe discharging onto brickwork is a damp problem in waiting.
Roofline work usually goes alongside whatever else is being done on the roof, which keeps the access cost down to one visit.
The usual signs are visible from the ground: paint that will not hold, board that has gone dark and soft at the joints, gutter sagging away from the wall, or birds getting in behind the soffit. The test that settles it is whether the board still holds a screw. Timber that has taken years of water at the back is often sound looking on the face and rotten behind, so it is worth having somebody get a ladder on it before deciding.
For most houses, yes, on maintenance rather than looks. uPVC fascia and soffit does not need painting, will not rot and handles the salt air along this coast better than timber does. On period property where the detailing matters, painted timber may be the right call and it is a legitimate choice, it just comes with a repaint every few years. You will get a straight comparison rather than a push towards whichever is easier to fit.
Four things, in order of likelihood: they are blocked with moss and leaf litter off the roof, the fall is wrong so water sits rather than running to the outlet, a joint has failed and it is leaking rather than overflowing, or the gutter is simply undersized for the roof area feeding it. A clear and a check sorts most of them in a visit. Diagnosing which one it is matters, because clearing a gutter that has the wrong fall changes nothing.
Yes. Gutter clearing on its own is a normal booking, and on a property with trees near it, doing it before winter is a lot cheaper than dealing with what an overflowing gutter does to a wall. While the ladder is up you get told about anything else that is visibly wrong on the roofline rather than left to find out in February.
Yes, and it is the main reason to do the job properly rather than cap over the old board. Once the fascia is off, the ends of the rafters are visible, and on a house where the gutter has been leaking for years some of them will have taken water. Anything soft gets cut back and repaired before the new board goes on, and you get shown what was found. Capping over a rotten fascia is the cheap version and it hides the actual problem.
Usually, yes. uPVC roofline comes in white, black, anthracite, rosewood and a range of woodgrain foils, so matching existing windows or a neighbouring elevation on a semi is normally straightforward. Bring a sample or a photo and it can be matched at the quote stage.