Buying a flat abroad through British LTD company

You can usually write a mortage off as a buisiness, if you buy it you have a more limited time span to pay it off.

Buying a flat where you live and work from a uk ltd(mostly non eu if you life there more then 6 month), and pay taxes in poland (at least when you work half the year+ from there). When you live there privately, you mostly doesn't get the tax advantages as airbnb tourist flat, you most likely add a realistic loan to your taxable income. As airbnb flat, it is something different but remember you often needs a license especially when you use it as the buisiness as a private person you are mostly in a better position for this. Working through the borders, might add some taxes too in future. It isn't so easy to convince a polnish bank to give a mortage to a uk enterprise with limited securyties and again brexit. (usually you open an polnish enterprise for this, or get an mortage for an flat/house in england to pay off the new one in a different country with interest rates like you buy a new house/flat)

Cash rules. You will get a better deal, you can haggle to get a lower price. Atleast in UK, but not sure how it works in Poland.

rent it on Airbnb

This might be a simple option, but income generated on Airbnb will be classified as company income and will be taxable.

work remotely from there.

This will be a complicated operation and my advise ( and if you have an accountant ) will be to stay away from it. This will be classified as benefits under UK tax regulations and you will need to pay class 1 NIC. So not worth it.

And getting a mortgage for a LTD company in UK, you will only get a Buy you Let mortgage whose purpose is primarily to recycle your rising equity (ideal condition) in the house by remortgaging. In UK because of restricted house supply this is ideal, not sure if it the case in Poland. Secondly you might ask Polish lenders too. I think it will be simpler if you do it through a Polish entity rather than an UK entity. But doing this is going to complicate your LTD company tax matters, so think before you leap into it.

Why buy through British agency when you can use Polish one with lower rates (because their profit is in zlotys and not pounds and LTD company will bil you for all the things mentioned below)

Taking a mortgage in Britain and buying in Poland may be troublesome as this will be extra cost of evaluation and pricing between British bank and polish appraiser (who would probably need to translate all documents with sworn translator).
It is always better to buy with own money rather than mortgage because you don't pay bank cost. Also some banks forbid to earn money on bought property for a set period of time which could be troublesome if you want to rent it out.
And third is that you don't need any special permit to buy a flat in Poland (You would have large problems with house as Poland have strict land laws).