You need to apply for the Non Imm O visa. It's both the marriage visa and the visa for being 50 and over(commonly called the retirement visa). You'll need this visa to open a bank account and to apply for a yearly extension of stay.
The Non Imm O IS the 'retirement visa'(based on being 50 or over). What you apply for after is the 1 year extention of stay(again based on being 50 or over) technically not a visa at all.