It might , it’s a bit luck of the draw on weekends, sometimes RM process it and get it to you next day but sometimes they loose it for a couple of days.
In my experience (20+ buys from
Vendor) if you order on a Friday and it doesn’t come on Saturday it’s probs unlikely to arrive on Monday. So maybe worth paying the extra if u need it on the Saturday.
But I would say it’s all down to Royal Mail, 100% confidence these guys will send it if you order in time

normal 1st class can take weeks at times. Hopefully lands for you or hit dispute and can work out a resolution with the vendor. Well msg them first b4 dispute seems best ethics then seems to get sorted out.