That job looks about a 25 quidder, probably about 20 min job that. But i wouldnt be confident about getting it at that, theres definitely people that would do that cheaper....
Not that i would do it as i stopped doing skylights altogether i hate them, everything settles on them, then the sun welds it on and you cant put any pressue on the glass.
Last house i did had 4 skylights on the extension, i cleaned them all on a first clean spent ages.
Went to do the second clean, messaged her before hand and she said could you do the skylights as they wernt done last time
I just chalked it off the round, said goodbye to skylights an vowed never to do them again.