Is it permissible to pay the baker 50 pounds in advance to receive bread worth one pound daily (30 pounds monthly), given the crowded conditions and difficulty in obtaining it, and is this act lawful or unlawful?

It is permissible for the buyer to agree with the baker to purchase a known quantity of bread and pay the price, then take a portion of it each day until the agreed-upon quantity is exhausted. This is considered a sale, not a forward sale (salam), so neither the immediate payment of the capital nor the delayed delivery of the sold item is a condition.