1. Austro Control should provide you with a letter stating which subjects you have passed and on what date, which should be submitted with your licence application to the UK CAA.
2. If, when applying for a FI certificate, you hold a CPL, that in itself is evidence that you have passed at least the CPL exams. You would only need separate evidence of exam passes if you were applying for the FI certificate to be added to a PPL and for this purpose, the validity of the exams is not limited.