I was extremely lucky in my UK hospital - DS1 had a mild posterior tongue tie but boy did it affect his latch! The lactation expert came to see me the second day, and she diagnosed it by running her finger under his tongue - it had already been missed by 2 other HCPs. I'd asked for it to be checked for because DH has one and there is an inheritable link.
So, because it was mild she said she could refer straight away or I could give it a couple of days to see how her feeding techniques worked out.
Luckily for me, MW who came to see me was also a bf'ing expert - she listened to the tongue-clicking and the length of time it was taking for DS1 to feed (up to 2h), and she made the referral for me.
Within 2 weeks, I saw a paediatrician about it - he said it was mild, but he'd known mild tongue ties really affect feeding, and snipping helped; he'd also seen really severe tongue ties snipped and it had no effect on feeding, so he gave me the choice. I said "Do it" because I wanted to give DS1 the best chance (TT can also have effects on dental health and speech). It made the world of difference!
I was also asked to fill in a feedback form re. the outcome of the tonguetie snip - which I happily did - because the paed in question was doing some kind of survey on the effects of having it snipped compared to severity of tongue tie. I wish I could remember his name so I could see if he'd published anything!
In Australia, I pushed to have DS2's tongue tie snipped before we were discharged from hospital, but it just didn't happen. :(
It took 5 weeks to see the paed, and we were lucky we got one who knew what he was talking about, as opposed to the idiot who told my friend that "all babies have a squareish tongue, tongue tie isn't relevant to your baby's reflux, and is just a "buzzword" at the moment" and made her take her baby off BM and go onto thickened formula instead. :(
Paed snipped DS2's TT, his feeding improved but not as quickly as Ds1's, because he'd had longer to get into bad latch habits (5 weeks as opposed to 2) - but still made a massive difference.
I passionately believe that tongue tie should be routinely checked for at birth, same as hip dysplasia, hearing and sight checks. And, if found, it should bloody well be dealt with - the health services are apparently keen to get breastfeeding rates up, so why the actual fuck won't they take this very easy, very cheap and extremely simple step to make feeding easier?
Feeding a tonguetied baby can be excruciating - for me it was like having razor blades sucked through my nipples - and it's only because I had the tongueties dealt with that I managed to carry on bf'ing as long as I did.
I'm also extremely irritated that many hospitals in the UK won't do it routinely, but insist on charging £100+ to have it done privately in specialist units - again, I can't believe how lucky I was to have a sane team in the hospital I had DS1 in!