All banks can send it via electronic transfer, which takes three days, and there is no charge for this. So if you send it Tuesday it will arrive at IB's UK bank to clear at close on Thursday, and I would expect funds to be in your account ready to trade with on Friday late afternoon at the latest.
Remember that you are sending it to the UK bank which notifies the UK IB office, which in turn notifies the US IB office, which credits your account. So do bear in mind the 5 hour time difference between UK and US, and the number of processes it has to go through. IB's US office opens at 2:00pm UK time, so therefore it will take them an hour or two to go through all the credits which have arrived, hence you might not have credited to your account until 5:00pm UK time.
Just make sure that you complete the online funds deposit notification form, and check with your bank the cut-off time for transferring funds by this method. Mine is 18:00 UK time, but the deadline for CHAPS (£18 fee) is 14:30 for same-day transfer.