£10k as final balance in your latest bank statement, you must upload the pdf file of your bank statement not a screen shot. MUST be a statement from a UK bank.
Up to 90 days before arrival, it is single entry and gives you 90 days inside Thailand. On arrival you should open a Thai bank account and deposit a minimum of 400k baht. 30 days before your stamp runs out go into your local immigration office and get the list of requirements for a 1 year extension