By 'rides' I’ll assume you mean 'slips', which then slowly allows the car to build up to speed (as in, the rest of the car catches up with the engine). There are two major causes of this, the first is a clutch that is out of adjustment, and the second is a clutch that really needs replacement.

The problem you have, though, is that even if the clutch on the Barina is adjustable (and some clutches aren’t) the fact that you’ve been driving it with the clutch slipping suggests that you’ve already damaged the clutch to the point where it would need to be replaced anyway. Continuing to drive it can also put 'hot-spots' on the car’s flywheel (to which the clutch attaches) and that can mean the flywheel also needs to be resurfaced when you replace the clutch.

I reckon, at the minimum, you’re looking at a new clutch kit. Ignoring it will eventually wind up with the clutch expiring completely and you walking home.

The Barina will run happily on E10 and I doubt the dealer's advice about the "emission light". Ford, on the other hand, recommends you use the higher octane rating premium fuel, hence the advice not to use E10. Your Focus will run on E10, probably without any trouble, but it will run better on premium unleaded.

HAVE you switched fuel recently? A change of fuel can have the effect you complain of. Of course, it's worth checking the basics to make sure the engine management system is doing what it's meant to be doing, particularly during the cold phase.