So you probably already have decently-growing cucumbers at this point but I wanted to weigh in on this.
If you planted the seeds upside down they'd mostly right themselves and grow the right way. Robert Krulwich from NPR had a good post on this here.
A sideways seed won't have to right itself so it will shoot up faster.
The cling film helps to do two things - hold in some heat and moisture. Dry seeds don't sprout and spouted seeds that dry out will die. If I start seeds inside I'll put them in a small "mini greenhouse" that is nothing more than a container with a plastic lid to help regulate the moisture level.
But with cucumbers, unless I'm making seedlings to sell/give away I'd just direct sow them once the soil's warm. Indoor/greenhouse seedling growing would jump-start that a bit if the ground is colder in your area.