Sorry to hear about the poor luck with the weather.
Your wire halyard should have a “soft eye” (wire loop) at the end, with a rope tail spliced onto it. (The rope part is just to stop you losing the wire irretrievably inside the mast, but importantly takes no tension when sailing.)
When you want to rig the boat, you pull the rope tail (which you have thoughtfully tied a stopper knot in the end of) and the wire halyard emerges from the base of the mast. It then runs directly up to the Highfield lever and loops onto the hook.
The Highfield lever should be at just the right height so that you can manage to hook the soft eye onto it without too much effort (bearing in mind that if it’s a bit windy the genoa may be flapping a bit, which makes it harder to loop the eye onto the hook.) If the Highfield is mounted too low you can’t get enough rig tension, too high and you can’t get the loop onto the hook!
There’s a trick to tensioning the Highfield – if you get your crew to pull firmly on the forestay (with a gloved hand) this relieves tension from the halyard, and makes it easier to close the lever (upwards, as you guessed). All the same, mind your fingers!
I’m in Plymouth on Friday 18th and again for a couple of days the week after next, so if you’re around feel free to text me.