It is a fact full stop that a jury can hold it against you if you unreasonably delay giving important information - it's not my opinion.
You should not sit down and talk to the police unless your lawyer is sitting directly next to you. Ideally, your lawyer should contact the police on your behalf with your alibi and you should never directly talk to them.
We can't realistically keep a jury from holding that against you the same way that we can't realistically keep a jury from randomly misinterpreting the law, or convicting someone just because they're black -- but we make it clear to them that they're really not supposed to. And the risk from talking to the police without a lawyer present is much higher than the risk of a jury punishing you for exercising your 5th Amendment rights -- you should err on trusting a jury to do the right thing more than you should err on trusting a prosecutor to do the right thing.
No we don't in the UK.
So the basic advice not to talk to the police holds.
Do not take this advice. Talk to a lawyer.
If you have an alibi, you can tell your alibi to a lawyer, and your lawyer can communicate your alibi to the police before you go to trial. You won't be wasting anyone's time, you'll just be giving the police the same evidence through someone who is trained to talk to police officers, and isn't going to accidentally say something that's misinterpreted or twisted to turn your life into a nightmare.
If you are being suspected of a crime, it doesn't matter if you're innocent -- the police are not your friends.