New set-up - router and mesh

[#1]

I've had an AirPort Time Capsule 802.11ac for the last 5-7 years. I tend to use cloud storage now plus a local hard drive and I think it's fine to upgrade. We get 60Mb normally downstairs near the router but up in our loft room it only hits 5 on a good day. I was thinking if wifi 6 with mesh. Has anyone got a recommendation? I've looked at the BT Premium and the TP-Link M9. My work will pay a reasonable amount as I work from home all the time now.
Another question - I have a modem and a router. Do I still need both if these? If not, how do I connect?
I'd appreciate any replies! Thanks!
Philip.

[#2]

If you get the BT ones you'll need to plug them into the router whereas the M9 replaces your router and plugs into the modem.

I've got the standard BT ones (little write up here https://community.plus.net/t5/Tech-Help-Software-Hardware-etc/BT-Whole-Home-Wifi-with-PN/m-p/1652505...)

Also I'd look at Backblaze for offsite backup - cloud storage isn't a backup.

[#3]

Thank you. Also for the recommendation of Backblaze:)