No it's the right page. But the option Terpe mentioned isn't listed.

You need to select the first option, Other Visa Category. I know this is the correct category to select as I had the same question and asked VFS to confirm the right category I should select prior to applying.

Prime time appointments are appointments which can be chosen usually at shorter notice and can include Saturdays (paid). For the purpose of a partner visa application I do not think you can make a prime time appointment although for most of the other visa categories you can.