Are these white bolts the way to the toilet fill valve?

Are these white bolts the way to the toilet fill valve? Trying to replace the fill valve on my toilet, and I have already asked about it here in other words, want to check my approach first. Photos attached. Close coupled cistern, blue float fill valve, fed by a flexi hose not a hard pipe. On the shelf inside there are two round white plastic things, one with a slot in it, one that looks like a plain cap. I'm assuming those cover the bolts holding the cistern to the pan, and that undoing them lets me lift the cistern off to reach the backnut under the fill valve. Is that right? Also, do I even need to lift it? Can't get a spanner near the underside otherwise, but happy to be told there's a trick. Plan is isolate at the valve on the flexi, flush, sponge out, new doughnut seal on reassembly. What else should I watch for?