For questions imo you should be able to rattle through 5 mock tests in a row without more than 1-2 errors each, and even then you should look up those errors. Definitely be confident with your stopping distances on dry, wet & icy roads and revise ALL sections of the test, even the boring bits that likely don't really apply to you like caravans (I got stung with about 4 caravan Qs my first time and I'd just ignored them, silly way to fail/pay money) (edit - revise where and what sides of the road you can park on, obv NO ONE follows this in real life, but it can be in the test)
For road signs I didn't really bother as tbh MOST of are self explanatory or variations of a type (like speed limits) but its worth just going through lists of them to see if any jump out as 'WTF does that mean?' then you can look it up. (I should add that I learned to drive a bit later in life, so I had decades of passive exp with roads and roadsigns in general, even if not a driver)
For the hazard perception my main advice is don't overthink or stress, MOST of the hazards are pretty clear, vehicles quickly merging from the sides or bikes/pedestrians about to do something weird in front of you, quite a few with blind corners & junctions to spot as well, you might still get a few surprises but that covers most of them. Don't be tempted to mash the screen as it does fail the Q but you do have some wiggle room for clicks so not the end of the world if you're a bit early or make a mistake, in 3 tests I've only had a Q fail for over clicking once, and it still only takes a few points away and I passed ok. (I did no hazard revision for any of my tests and passed all 3 times)