Carry money in a Lidl/Aldi carrier bag, dress really down, that way people don't think you've got 2 pennies to rub together. And always, but always look round before you do anything. Imagine that you're being followed and act accordingly.
I never have trouble exchanging up to 5K into PLN, even if I have to go every day. You have to deposit money in a bank pretty quickly or go straight home (with your Lidl/Aldi carrier bag).
you can keep £5K in a pocket easy, just spread it around a bit, wear some combat trousers or something, i prefer to keep it in the inside pocket of my jacket.
I take the money in £1000 lots - I took £10k once and it came up short £130 when they counted it. They ripped me off.
That happened to me at a bank, i was paying in 40,000 PLN, the lady behind the counter who looked so sweet and innocent said "thats a lot of money". I paid no attention and carried on talking to who i was with. Sure enough it came up 200 PLN short, now i wasnt in a position to argue as i didnt count the money. Later i questioned the counter and he said 100% it was correct.
Ive been back there a few times with large amounts hoping she will do it again, but not successful as yet. I'll catch her one day. Now I also watch them like a bloody hawk, if you dont thats their opportunity to slip a few notes under the table.