The accounts up to 31-Mar-2022 (ie just before flights launched in a serious way) are due at Companies House by 31-Dec-2022, and will likely appear on the web by early January. This will show the costs incurred in starting the airline and other interesting info. If you want to see *reliable* operating financial data, then expect to wait another 18 months
If you have access, RDC Apex should give good estimates
Otherwise, CAA data is all there is in the public domain