Haha, I too find myself checking the exchange rate on a regular basis hoping it stays around 1.40ish in mid-July/early-August time. It did go as high as 1.42 a month or so ago!
I've just done a quick check and my bank has the exchange rate at 1.3468, whereas Transferwise has it at 1.3941, which is much much muuuuuch closer to the actual rate.
So an example transaction of $15,000 would be £11,137.51 with the bank (+ any transfer fee) and £10,759.63 with Transferwise, as of 11.15am UK time today.
Obviously the exchange rate changes during the day and you pay a small refundable % based deposit with Transferwise to allow for any movement in the rate. They automatically pay the refund into your bank account, so there's no issues with that at all.