Remittance basis vs Arising basis for oversea savings with interests

I am paying higher tax rate in UK and become tax resident for 2 years. I have some savings overseas before I become UK tax resident which generated interest in last tax year. The bank, however, did not separate my principal funds and intest into different account. 1. If I choose remittence basis for the interest earned overseas, when I transfer the money from the account into UK, will the whole some of money charged with higher tax rate? (they become mixed fund). 2. If I choose arising basis and pay the tax for the interest earned overseas. Will there be any tax generated for the money transferring into UK in the future?

Hi,
Please refer to Paying tax on the remittance basis (Self Assessment helpsheet HS264)
Thank you.