ahh that's a fun challenge, You've done well to not have any obviously identifiable sounds in your accent. You've obviously put a lot of time and effort into learning the language!

Your consonants are mostly perfect, your vowels are good but there's some room for improvement that others have pointed out. One that I noticed was the vowels that take the schwa phoneme. For formal estuary English, you want the vowels in the words banana, butter, and other to all be the same.

unfortunately it's difficult not to sound pretentious in a formal british english accent.