Hoping they don't expect me to register as Tier 2 and have to pay the £150 something fee to use their sites for disposal. But I guess I'll find out when they pounce on me as I arrive at the managers office
Tier 1 or lower tier is used when transporting your own waste. That being waste you generate in your own business (these containers are in that bracket). Everyone should have one (its free) as even buying a Mars Bar, and putting it wrapper in the van door can be classed as transporting waste.
Tier 2 (or upper tier) is used when transporting other peoples waste, like house clearance, bags of rubbish from cleaning jobs etc.
Be aware that the tip may have a minimum payment, especially if you're having to go over the weigh bridge. Typically, this is about £70 to £80 inc VAT, but it varies. If you have no luck there, start ringing around the local skip companies, and ask them if they have a 'waste transfer station' and let you bring your waste in to them. That way, you can talk to someone who isn't a robot, and come to an arrangement.