Welcome to the forum. Light up a portfire and join in the fun.
I think you'll find that the members here who run fireworks retail businesses go direct to the firework companies rather than through intermediary wholesalers / trade suppliers. If you do want to go down the cash & carry wholesaler route, then Makro and JTF supply fireworks.
If you want to go direct to the fireworks company, then a web search for a brand should bring up websites and contact details for those that are internet savvy. Also, some of the fireworks brands will be exhibiting at the Spring Fair in the NEC at Birmingham in a couple of days time. Our retailer members might also be able to give additional help - either by posting here or via the PM system.
I've seen your name on the "new member" list for a while..... so have you taken the opportunity to browse through the forum yet? There have been some topics on starting up a retail fireworks business recently that are worth reading for guidance on all the other issues that have to bve considered - like storage and insurance etc. Let us know if you've read those threads - it might save you from being bombarded by repeats of stuff you've already got your head round.