subtax

I have a CASH ISA account from last year and i was saving in it till May 2024. After that, i have opened a new CASH ISA with another provider for better interest rate. Can i still continue saving in both Cash ISA? Or i should close old one and transfer my money to new Cash ISA and use the new one only for future savings? With new rules in 2024, can i open a new stocks and shares ISA this year and operate it alngwith my old/new CASH ISA?

I live in UK and work from here for UK company. I used to send money to India from UK in my NRE account. I have earned around 800 pound interest in NRE account in last UK financial year. Do I need to pay tax in UK for this amount in case i want to bring the money back to UK now or paying tax is required only when interest income is beyond 1000 pound in an year? If i need to pay tax in UK, then could you please share the process how can i pay tax for this in UK? Also, NRE interest is not taxable in india. But while paying UK tax for this interest, can i still apply 15 percent credit as per DTAA agreement?