I came over here and ended up having 90 day tourist visa. got all the retirement Visa and everything sorted while I was here including the bank account.
It's entirely up to you but it seems £300 per month is quite a lot of money. Personally if you're healthy I would put the £300 a month into a separate bank account and self-insure you can always use the 800,000 deposit in your bank account for any big bills as long as it is is replenished by end of renewal.