Estimates/Line Length Question for Fibre

[#1]

Hey guys, new to PlusNet and eagerly waiting for my house move date so I can finally move onto Fibre from 3Mbps ADSL
On the orders page for PlusNet it gives me the low estimate taken from the Wholesale checker but because the estimate is just below 40Mbps it won't allow me to order an "Up to 76Mbps" package.
I understand estimates are estimates and it's pointless to allow 30-40Mbps properties to order "Up to 76Mbps" but I've seen quite a few people with similar line lengths of 600-650m that are around the 50-60Mbps range for their download and on the Clean (High) side of their estimate. I also just need to quickly note that before the PlusNet page was giving me an estimate of 54/14 and allowed me to proceed with an 80/20 package but the past week the estimates seem to have changed and now I'm blocked off.
I've included some attachments from the Wholesale Checker for the property and 2 ways the line could possibly make it's way too the cabinet along with an estimate length.
I've also seen a user from another forum who has incredibly similar wholesale estimates to my own and a similar line length and is almost on 60Mbps speeds. (example1.png)
So my question is how would I go about getting myself on the Unlimited Fibre Extra package once I'm moved in and what are my potential options?
I was planning on taking ADSL over with me to the new property for a week or so and then getting myself upgraded to Fibre.
Should I upgrade to the 40/20 package and see how the line fairs to begin with? If the line does tend to hold close to 40/20 would it be possible for forum staff to manually upgrade to the 80/20 package for me if I request it?
Cheers guys

[#2]

At a previous house, I had a line of 650m - the current FTTC estimates for that property are slightly higher than yours, by around 5Mb in each category. That place has 0.5mm copper feeding it, and is around 20 years old, so is in reasonably good condition.
You might find that your line is the shorter route, but has some chunks of aluminium or thinner copper.

[#3]

Property I'm moving to is literally brand new, the times I've gone to look round the property I've noticed there's no line hooked up at all so I can only imagine the line installed is going to be cheap and dreadful.
I hope it's on the shorter route, I might bribe the engineer that turns up with some coffee or tea and see If I can get some info on the line

[#4]

Usually the worst lines are those installed by builders. If Openreach have to start yours by pulling the cable through ducting from a manhole (or overhead from a pole), then your likely to have reasonable copper for the lead-in or drop wire, at least.
But for the segment back to the cabinet? Who knows how old, or what routing it take... so its certainly good to find out proper distances, routing, and attenuation values from the engineer when he turns up!