This one also states: "Openreach estimate that the distance to the fibre aggregation node serving your premises is 0 - 199m.", would I be silly to hope that this short distance would mean my final quote could be much less?
It does seem a lot. However, the line-of-sight distance may be 200m, but the route on the ground could easily be twice as long, and it depends what already exists along that route.
My original quote was £13,700, which was one of the very early ones. This reduced to £6,600 on survey, and it included 34m of new ducting (in a quiet lane). The rest was supposed to be existing ducts. In the end, one of the main ducts was full, and they had to dig a further 164m of new duct... that would have been very expensive for them.
It's possible that in the light of nearly 2 years of experience, their desktop quotes are coming in closer to the actual costings, and/or the costings from survey have gone up to be more realistic. Few people have reported their findings here recently, but in the latest one (Jan 2020) the price actually went up from £6,800 to £8,640.
You have to take a gamble. What's the maximum you would be prepared to pay for the installation? If you are prepared to pay, say, £8K(+VAT) up front for the installation, plus £100+VAT per month for the first year, then you can probably afford to gamble £250+VAT on the survey.
It would hurt if the final quote came out too high and you had to abandon the order, but it's only equivalent to the first two and a half months of line rental.