You are right, I'm Polish. My "home" spot is Zalew Zegrzynski, relative small lake near
Warsaw. Sometimes, if I have spare time, I'm going to Zatoka Pucka, bay on the Baltic Sea.
On my spot wind is really light (8 knots 2 days a week, 12 k maybe 1/w) but very gusty and twisty. Sailing formula on this lake is neverending outhaul adjusting, keep out, change stance, reacting for changing direction of wind and terrible chop. Its great! Only problem is pure race sail 11.4 Naish Stealth, landing on water frequently. I'm not experienced windsurfer, so to pay attention is not enough for me
. I have also 9.5 NP Slalom MkIII, very nice light sail, but a little to small for my heavy weight on wind below 15 k. I hope 8.5 Helium and smaller board will be easier to control and... easier to uphaul
P.S. Have you ever been on Zalew Zegrzynski? Where are you sailing in Belgium?