so if i will send BTC/GBP from exchange what will i receive on another exchange BTC/USDT ?
You're spelling it wrong. If you transfer 1 bitcoin from one exchange where its price is listed in GBR (it is currently worth ~29899.63 pounds), then on the exchange where bitcoin is traded to USDT, there the price will be ~37743.61 USDT for 1 bitcoin.