just hope it is not an old take away number
What is a take away number please ?
Fast food outlet where you phone up to order food for delivery
If the number hasn't yet been routed to your daughters address in Openreach's databases , then although using the phone number to get a speed estimate is usually the most accurate, in this case ( as the line is only part way through its provision process ) using the post code will give a quicker guide to the likely speed , or wait until the line is properly installed....if your daughter is getting line and broadband , then BT should gave already given her a speed estimate.
Try the post code here
If it's just a case of changing provider rather than moving address, the speed the new provider delivers will pretty much be the same as the old provider speed , providing it's based on the same Openreach product 40/55/80Mb, but if getting 35Mb , the higher 2 products may be pointless , as if the line can 'only' do 35Mb , buying the 80Mb product will still only get 35Mb (download)
Something to have in mind, is the speed can be less with the new provider in the first few days , but should recover to at least the previous provider speed