visa for spouse of chinese national

I am retiring soon and am married to a chinese national. i was married in china and we have a flat there. we wish to semi retire in China spending 6-9 months there and 3 months in the Uk. (she has permanent residence in UK) but she is registered as being in china. i have looked around for the forms for this new family or spouse visa . I am over 60 so qualify i believe. what form do i need to fill in. i have heard that before they sometimes extended the visa for people like myself unoffically but would like this done offically