Gigafast questions - confused by callcenter

I currently have BT FTTP and I was looking at Vodafone Gigafast as they're significantly cheaper. However the conversation I had with the Voda callcenter left me a bit confused.

1. I asked how much disruption there would be on the day of swtichover. They said none at all. I asked them to clarify and they said that as soon as BT stops service, they start service instantly and I shouldn't even notice. I asked if that meant I could just leave the BT Superhub connected and they confirmed that was the case. I was expecting at least a few minutes of downtime and needing to swap out the routers at the least.

2. I asked about keeping the BT line and having Gigafast as a second connection - I have an ONT with four Ethernet ports so this is technically possible. They didn't understand the question and just kept repeating how there would be zero disruption if I switched from BT.

3. I asked about upload speeds since they're not listed on the site. They said it was fully synchronous - if I went for Gigafast 900 I would get 900 up and down. I asked if that meant the line was going to be CItyFibre rather than Openreach and they said it would be both. So that sounds like CityFibre (but why insist on ceasing my BT service?)

4. I asked about install lead times - CItyFibre are in this area, but their closest cabling is 5 streets away. They said it would take 10-14 days and wouldn't require an engineer visit. Surely it would take more time to run the fibre, and some people to come do the work? If that means it's actually Openreach, then surely I can't have 900 up?

All in all I left the call feeling more confused then when I started, and I'm suddenly much more wary about Voda as a provider (though I shouldn't necessarily equate one single sales person with entire organisation).

You could try posting in this Vodafone forum. Some of the replies are from Vodafone staff.

You really need to establish if this will be a Cityfibre network because if it is they wont care about the BT line, in fact when I signed up for my Cityfibre (Vodafone) install I didnt make any mention of my BT/Openreach FTTP line, I currently have both.

They havent helped their staff by having a Openreach provided gigafast service, its obviously causing all sorts of confusion. If its only openreach FTTP you can get it wont be asynchronous.

Whats your town/city and postcode (PM if you prefer) and I'll see if I can tell.

It really is causing confusion!

I'm in Glasgow, G40 4TP. New build house, Openreach FTTP was fitted during the build so a 4-port OR ONT was already present when I moved in.

CItyfibre have cable a few streets away, but not close enough for service according to their own checker.