Is my compost heap a go-er or a dead loss ?

[womble]

Honestly, forget the worms. If you have the right conditions they will come and breed in more numbers than you can imagine, you literally will have the compost crawling with them within a very short time.
And if you buy worms, they will stay if they like it and go if not. So you gain virtually nothing.

[Two_Sheds]

in open large heaps , redworms or common earthworms.

There are loads of different worms

"Tiger worms (Eisenia foetida) and Dendrobaena, [are] proven to give a better overall composting performance..." Composting and Wormeries - Worms and Supplies | Worms Direct

The common pinky grey earthworm - Lumbricus terrestris - lives in the soil, pulling leaves & other organic matter down into its burrows to feed. It tends to stay in the soil, while the composting worms will migrate up into compost heaps