Can any scotland based... or Perthsire based people, recommend anyone for battery upgrades?

[GoCoeGo]

I have a very unusable 80ah leisure battery. And after slowly ironing lots of other things with the dealer i got it from (still ongoing but separate story) I am getting round to other things and upgrades... I'd like to move to lithium with an inverter, but I don't feel comfortable in picking the correct one myself. So if any funsters have some recommendations of where I could go. I'd really appreciate it. Thank you!