Get the paperwork stack right first
SIA badge, EFAW in date, passport-sized photos, right-to-work evidence, National Insurance number, bank details, references. Employers judge you on how quickly you can start.
Where the entry-level jobs really are
Events agencies (music, sport, conferences) hire in bulk and train fast. It's antisocial hours but the volume means offers.
Retail loss prevention chains (national supermarkets, DIY) have structured trainee programmes.
The first-shift playbook
Arrive 20 minutes early, uniform pressed, boots clean, notebook in pocket. Do exactly what the shift supervisor says. Ask sensible questions during breaks. That is how first shifts become second and third shifts.