If you're hoping to change old banknotes (and/or old coins) into their newer equivalents in a bank, don't expect to just walk in with the old money and get the new stuff in your hand straight away.
I went into Barclays today with £90 on old fivers and £247 in old pound coins. (I'd emptied my piggy bank!). I had to queue for ages before being told that
(a) I'd have to pay the money into my account and take it out again. (I couldn't do a straight swap) ; and
(b) they couldn't accept the pound coins until I'd bagged them all in up into multiples of £20.
So I had to sit in the bank and count all of the pound coins into plastic bags, then queue all over again, wait for ages while the cashier weighed and re-weighed the bags, pay the money into my account and then withdraw it again.
In total it took just under half an hour to get new for old!