I purchased a second home in Dec 2020 but can't visit until 12 April due to COVID rules. How can I find out whether it has a landline and whether it is active without visiting?
Its not possible to do that, however if you use the online ordering page, it should give you some idea whether there is an existing BT Retail service.
Its a good idea to place an order now, so that service will be available when you need it.
Place an order for a line only using this link - https://www.bt.com/landline/deals
You may still have a line into the house but I very much doubt is still active as the previous occupier would have had the line stopped. If not they would still be paying for it.
Wouldn't it be possible to simply contact the previous owner, albeit via the estate agent if necessary, and just ask them what the situation is as regards the existence of a landline or not?