My other half and I are having terrible problems with the new BT Mail on our laptops (works ok on phone and IPad), even though we've tried on several browsers (Chrome, Firefox and Microsoft Edge - latter recommended by BT). As well as looking awful and over-busy (which we could just about cope with), if I delete more than one or two emails at a time it greys out and says 'loading' - often for quite a long time. Also slow to start. Also, if I click on to one email, sometimes a completely different email appears (that one is maddening). We are so desperate that we're happy to pay at least something to use some reliable alternative or third party system, so long as we can keep our email addresses. It really has been going on too long and although BT staff charming, nothing has resolved the issues. All recommendations welcome. I am not that tekkie but not a complete dunce.
If you are happy using an email client/app on your phone and iPad why don't you set up an email client/app on your laptops. This would mean that you would not need to log onto the BT webmail and use it that way. You would use the email client/app in te same way as on your phone and iPad.
You could use the Windows Mail email client/app that is probably already installed on your laptops or you could down load an email client such as Thunderbird.
If you do decide to use an email client/app, which are easy to set up, the settings you need are here.