You can ask to migrate data from Sage 50 or Xero to QBO UK version for free.
https://quickbooks.grsm.io/UK
For other Sage editions, you may have 2 ways:
1. Prepare your data in XLS/CSV and utilize an importer tool
https://transactionpro.grsm.io/qbo
2. Purchase a 3rd party conversion service.
Contact us in private for details.