According to Appendix FM of the Immigration Rules, an unmarried partner of an applicant is a person who has been living together with the applicant in a relationship akin to a marriage or civil partnership for at least two years prior to the date of application.

You should use application form FLR (FP) to submit an application for leave to remain as an unmarried partner under 10 years route.

Yes, you can switch from from unmarried partner under 10 years route to unmarried partner category under 5 years route from inside the UK by using application form FLR (M).

No, the Immigration Rules do not require an applicant applying for leave to remain as unmarried partner under 10 years route to meet the English language and financial requirement.

If you are lawfully in the UK and are switching from another category to 10 years unmarried partner route, you can submit your application through Same Day Visa Service.

If your application for leave to remain as an married partner is successful, you will be granted leave to remain for 30 months.

You can apply for Indefinite Leave to Remain (ILR) as an unmarried partner under 10 years route once you have completed 10 years in the UK continuously with leave to remain under 10 years route. Most applicants in this category will be able to apply for Indefinite Leave to Remain (ILR) earlier under 10 years long residence.

Yes, you will get right to appeal against the refusal of your application unless the Home Office UKVI certify your human rights claim as manifestly unfounded.

If your human rights claim has not been certified as manifestly unfounded by the Home Office, UKVI and the UKVI have not given you out of country right of appeal, you can appeal against the refusal of your application from inside the UK.

If your human rights claim has been certified as manifestly unfounded and you have not been given right of appeal against the refusal of  your application, you can challenge the decision of the Home Office UKVI by way of Judicial Review (JR) to the Upper Tribunal.