Normally a Faster Payment arrives within a few minutes, however sometimes the procedure can take up to two hours.
Please note that your Raisin UK Account updates at around 8 AM, 2 PM and again at 6 PM. So if you make a transfer at 3 PM, the earliest you will be able to see this in your Raisin UK Account will be at 6 PM. You may however not be able to view the payment until the next morning.