I bought my 25’x12’tunnel from Ferryman Tunnels in Crediton, Devon. Steph had suggested them to me. I did not get any of the extras that you mention but did get crop bars and thicker section tubes as my allotment is on a windy site in Exmouth.
Charles has an excellent discussion of poly tunnels in Learn > Articles
I have one 4′ opening door and one non-opening door, otherwise they are the same with a mesh (windbreak/scaffolding netting) cover. I have made frames for polythene inserts on the doors so I can have doors with all polythene, all mesh or half and half. Both doors have a 6″ gap above so there is always minimum ventilation and a route for insects. I can’t open and close every day so I vary the amount of ventilation according to the prevailing weather season.