thank you backinwellies. I
the JB boxes look good....but are their delivery charges very expensive? We will only need a few boxes
They're really nice people. Give them a ring and discuss. Tell them we're all saying how good they are - because they are, and we are

I did a heifer in boxes recently, so bought a small quantity of boxes to hold 10kgs meat. For a variety of reasons I ended up ordering three different types of box, which didn't all come from the one depot, as well as chiller strips ditto - so my advice would be to (a) make sure all the boxes will be the same, if possible, or at least come from the same depot - and (b) let the nice lady on the phone help you work that out to minimise your overall costs.
Fyi, even with my not very efficient ordering, it came to £7.30 per customer for the polystyrene box, outer cardboard packaging, chiller strips and delivery of said packaging to my butcher. Yes that's pricey, but the reactions to the very professional packaging were very good indeed, and for a half lamb or 10kgs beef, no-one seemed to mind paying extra for packaging of that quality - although a couple did ask could they reuse their box next time.
If your customers are collecting from the butcher you can do without the outer cardboard wrap, which on my figures would save nearly £1 per customer. And if you can ask them to bring their own chiller packs, that will save another 50p or so.
Oh, and if you are VAT-registered, you can reclaim the VAT on all the packaging and its delivery - and do not have to charge that VAT to your customers. So that would knock £1.25 off my £7.30.
HTH