You should not be seeing daylight between the gutter and the fascia. That will potentially let rain run down the fascia and not in to the gutter - and that will add to that awful efflorescence staining on the wall. Needs some plastic eaves tray it the roof is pitched or a drip forming if the roof is flat
I would use a piece of fascia to cover that. Cut it to a width so that it pushes that fascia out and keeps it straight not bowed like it is now, the 40mm section will go against the wall (stick with silicone) and will be within the soffit, the other end rests on top of that fascia lip again stick with silicone.
I would use a piece of fascia to cover that. Cut it to a width so that it pushes that fascia out and keeps it straight not bowed like it is now, the 40mm section will go against the wall (stick with silicone) and will be within the soffit, the other end rests on top of that fascia lip again stick with silicone.