Should I call my daughter Aoibhín in England?

Well, in the UK I have to spell 14 letters and it's tirening :) That's why I wouldn't wish an unusual name on someone.
It's fine while your parents do it for you though :)

What happens if you have the name Sean? Surely you have to spell it every time as how to the person on the phone know if you are a Sean, Shawn, Shaun ? (Or other even other ways of spelling it?) Steven/Stephen? Graeme/Graham?

The correct pronunciation is Eve - een .
Aoibh is Eve . My daughter is Aoibhe - Eva !

It doesn’t actually take any longer to say “Douglass with an extra s” than saying each letter though does it?

If you are providing your name to someone over the phone you will almost always spell it out in case the person on the other end makes a mistake. Let’s face it - many many companies now have call centres overseas where the staff are (naturally) not familiar with even common English surnames.

If the exact spelling matters then you will spell it even if your name is Smith (which of course could be Smyth) and if it doesn’t matter then it doesn’t matter.

How do Brits politely call someone, who doesn't think ahead?

It is the duty of parents to accommodate their kids by giving them names that can be easily pronounced phonetically in English, if they're living in an English-speaking country.
The names themselves don't have to be "English", they just have to be spelt as they would be pronounced in English. If they're not, and they're not widely known names, the child will face a lifetime of having to correct people - for which they can only blame their own stupid parents.

So you think parents who give their child a name that is not easily pronounced phonetically in English are stupid?
Charming.

Well, if it's 1 odd letter, you always can say "It's Douglas but with extra S", as I was doing with my last name in my country.
I would spare the child of "I'd better spell it for you" and "S for Sierra" dance for the rest of their life.

But I have to do that for my surname most of the time. There are about 10 different ways of spelling it phonetically. What is the issue? That is even before we get to my road name which is a whole other story!

I have a classic name but also need to spell it every time - it’s similar to Catherine.

There are very few surnames that don’t require spelling confirmation. Even in your example - Douglas can be spelled Douglass and a non-native speaker of English would likely omit the “o”. In reality this takes a couple of seconds. It’s not a big deal.

In school, it's not a big deal.
But every time I call insurance company/gp/bank/police/clubs, I have to spell my quite easy foreign name letter by letter, and it will never stop. While othe people can say "I'm Olivia Douglas" and that's it.

It's lovely you feel like that but not everyone does. DS is half Irish half Scottish and as English as they come! He has no interest in either culture (although an EU passport is always a draw)
I.have lots of Scottish and Irish friends who have raised kids in England and they go right across the spectrum of interest in their parents country of birth.

but having been told once most people remember. I am struggling to understand why people are so bothered by this. I worked with an Aoife. I didn’t know how to pronounce at first , I was told and for the last 20 years I know how to pronounce it without thinking. England is littered with place names (Bicester, Leicester, Holborn?) and surnames (beauchamp, Cholmondeley ?!) with pronunciations which don’t match the spellings. We mostly all know to pronounce them though and if we don’t we learn,

Use it as a second name so she can use it if she wants later on - or use an Anglicised spelling on a day to day basis even if officially its the Irish - we had enough trouble with Caitlin (we really didn't expect it having chosen the english way of spelling/saying) and more "Irish than us" cousins (Mom is Irish and they live there) have issues here with Oisin and Rohan and Dylan

Erin works, maybe Evelyn or Evie as a short name. To be fair irish names are definitely getting more common as is the ability to say them, but it does get tiring.

The problem is you lose the meaning of the name when you change the spelling. Aoibhín has meaning (even if only Irish speakers understand, maybe Scottish too?), but the spelling Aiveen is meaningless. And that can matter to people . (Aiveen is also a mispronunciation of the original Irish, but that is a separate issue.)

Here’s why we want to use Irish names that reflect our heritage. My aunt was given a copybook that was found when an old school was being knocked down. She was a primary school principal before she retired and the little girl whose copybook it was had the same surname as ours so was related to us. My dad was from a small town in Ireland and we have a usual spelling of our surname which is nearer the Irish spelling of our surname so we know she was related to us. The little girl is writing about her ‘news’, what she did everyday and what was happening in her life. For the first couple of months she’s Máire and then sadly she is using Mary by the end of the book. The English invaders had taken away her name which her parents gave her and which she would have used and heard everyday.

But I don't live in Ireland.
I bet you don't know how to pronounce Icelandic names either.

Both things are true. A child born to Irish parents is an Irish national and is entitled to Irish citizenship. If they are born in England they are also English. It’s possible to be both simultaneously.

How they feel and describe themselves to others is entirely their choice.

Im Irish and have 2 children living in England. My own name is a traditional Catholic one but not Irish. As a child born and raised in Ireland my Irishness was never going to be in doubt. Whereas it was important to me to give my English born children identifiably Irish names so that that part of their identity was clear to them and others.

What is interesting is I have an English name but it is a name that has variations in other countries. Every time I meet someone Spanish, Italian or French they pronounce it their way (even adding the extra consonants) and don’t even try to pronounce it the English way. I actually love that as it always sounds so gorgeous but it isn’t my actual name. Doesn’t even remotely bother me

Aoife. For heaven’s sake, your ignorance is not an excuse.

But what if your child fundamentally doesn’t care less about being of an Irish background? Citizenship is very different to identity.

Automatic grant of citizenship when born overseas is the norm for many countries. As I mentioned, my husband was automatically granted 3 citizenships the moment he was born. Which one is he meant to have allegiance to?

I'm an immigrant and was reading girl's name in my DC's class as Eye-oh-fee. Guess her original name. Aoibhin I would pronounce as Eye-oh-bin.

I would not use any traditional name that is not pronounced in accordance with rules of Englisin language in London, where 60% of ppl are immigrants. Unless you use it as a character building exercise.

I also had a Turkish friend born here and she was not happy how her very simple name was pronounced here and chose much easier but still Turkush names for her DCs.

I really do find attitudes on MN towards non-English (especially Scottish, Irish and Welsh) names perplexing and not at all reflective of real life.

There’s 2 different questions here :

1. should I give my child an Irish name when they will grow up in England (in my opinion, yes)
2. should I give my child a name I am pronouncing incorrectly and that is almost the same as the name of her sister (in my opinion, definitely no).

So don’t call her Aoibhin, but for reason 2 not reason 1.

I was responding to your comment "So do the English, every time".

In my experience, it's a very mixed bag. Since people twist themselves into knots to try and get it right, some people make no effort at all and call you some random nonsense, some people decide to call you by an abbreviation they make up. Most people make a reasonable effort and that's fine.

If you love the name, then use it for your DD.
I teach in a London school, and there have been many children whose names I didn’t know how to pronounce, in many different languages. It’s really not a problem, the parent explains the pronunciation, the other children pick it up really quickly ( faster than I do) and if I get it wrong there a bunch of classmates all telling me the correct way to say it.
In a less multicultural area, it might be different, but even then, given the fashion for more unusual names, I don’t think it’s the issue it might once have been.