What's your question? Ask

Breadfruit is an equatorial lowland species. It is ultra-tropical, requiring a temperature range of 16–38 °C (61–100 °F) and an annual rainfall of 200–250 cm (80–100 in).
It would not be suitable for Poland or for a greenhouse, they grow to a height of over 20 meters.

Here is a link that contains several articles about growing breadfruit. Be aware, though, that growing breadfruit from seed won't be same as parent tree. It is usually propagated through root cuttings or shoots.
https://www.gardeningknowhow.com/category/edible/fruits/breadfruit

As to buying the seeds, we are not a retail establishment and do not sell products. I would check with reputable online seed sellers or inquire at a local nursery.

I'm sorry, but no, we don't sell any products, only give out free gardening information.
If you can't find it locally, I'm sure you can find a reputable vendor online. I would only buy from a plant nursery, not an individual.

We don't sell any plants, seeds, or products. We provide free gardening information. I'm afraid we don't recommend vendors, either. However, your local extension agent may know some vendors.

I would caution you to only buy from reputable seed and plant vendor and not random individuals selling seeds online. We have seen problems with customers not getting what they expected. Read the reviews.

Here is an article for more information:
https://www.gardeningknowhow.com/edible/fruits/breadfruit/breadfruit-seed-propagation.htm
https://www.gardeningknowhow.com/edible/fruits/breadfruit/seedless-vs-seeded-breadfruit.htm
https://www.gardeningknowhow.com/edible/fruits/breadfruit/breadfruit-tree-facts.htm
https://www.gardeningknowhow.com/extension-search