Hi timi,
Good news and bad news.

The good news is that the health surcharge does not apply for Fiance(e) applications as the Fiance(e) visa is only 6 months max.

The bad news is that they'll get you after you get married and make the application for the FLR(M)
Which is a visa longer than 6 months. In you case it'll be 30 months

In fact it will apply to anyone making an application for Further Leave to Remain regardless of when they first entered UK
It will apply right up until application for ILR