I had this a few years ago. Extension to the house. Gave the guy 2k upfront for materials. Had emails, texts, everything to prove it. I ended up having to sack him as he was never turning up, drunk, no messages saying why he hadnt turned up etc..last straw was a support beam going above the kitchen, new kitchen being fitted a few weeks later so wanted it done before that. The beam wasn’t in place 2 days before (after multiple failed promises to do it) and he didn’t give a toss so I ended up having to get someone else in and sacking the original guy. I never saw the 2k, took him to small claims which happened to be during covid so they couldn’t be arsed and dismissed the case even though (I found out later) he had previous for this.
Either the workman pays or you pay the supplier direct and get it delivered to your house. At least if you have to sack him you have items you paid for.
Before anyone asks the guy was a nightmare and was constantly not turning up but we were well into the job and eventually I just had to say enough is enough. Beam went in the day before the kitchen and plastered the night before!!