I believe this is generally not necessary. You are not expected to sort out all details about your alternate. My checks are usually limited to “is it suitable for my aircraft” and “is it open”.
I would agree.
They will get copied on the flight plan anyway if you name them as one of the two alternates, and they will know what that means. Some airports (very few; I think mostly military ones) prohibit being specified as alternates.
In some cases, especially Italy or Greece, if there is the slightest chance of really taking the alternate, then I would check they have avgas and check opening hours, because you will spend € thousands getting avgas shipped there in 200 litre drums 
Incidentally, does LFAT need prior notice? They say they need one for Customs (i.e. a visit from the UK, Norway or Switzerland) but in practice probably 99% of visitors don’t do it. I’ve never done it.
Remember that the flight to the alternate is a full emergency. You are required to be able to fly to the alternate (I vaguely recall that the UK and possibly the USA does not require an alternate nominated for a VFR flight, fixed-wing, in certain circumstances, but not thinking about that is just stupid) but you are not required to be able to fly to the alternate and then (if they tell you to go away) fly to a second alternate. So if the first alternate refuses you a landing clearance you are entitled to declare a mayday. Obviously if you have tons of fuel etc etc and aren’t bothered, then may as well go somewhere else…
Remember that the flight to the alternate is a full emergency.
Really? 
You are required to be able to fly to the alternate (I vaguely recall that the UK and possibly the USA does not require an alternate nominated for a VFR flight, fixed-wing, in certain circumstances
The FAA even do not require an alternate for IR under specific weather conditions (TAF)
Remember that the flight to the alternate is a full emergency.
I remember that ATC made quite a fuss about it in Greece, on two occasions. They wanted a specific reason why I diverted. I also remember that they asked an Easyjet crew in the missed approach why they went around. They answered “’cause we f*cked up” which ATC didn’t understand at first
In my opinion, one shouldn’t set his mind on preselected alternates. In 99.99% cases one does not have lost COMM and when a landing at the destination is not possible, all options should be evaluated in flight and the preselected alternates are just options. Therefore I usually just pick something in the vicinity but I work out in flight where I want to land.
Sometimes alternates are even the real destination. Think hard why Netjets Europe is based at a VFR aerodrome right next to Frankfurt! (Hint: you do not need a slot for an alternate).
When I fly rotterdam to pula dutch customs (not immigration!) expects me to file a document.. (This was pre EU). I needed to file the same document when flying to Guernsey or Jersey..
A few months ago we flew Stuttgart to Lubljana ,alternate one Portoroz, alternate 2 Pula.
In flight we decided not go to Lubljana (some weather and the person we wanted to visit was not there) so we went for portoroz .. However Then Padoa (we were still in italian airspace said that Portoroz would close at eight and we were expecting 20:07 for Portoroz so we diverted to our second alternate (who accepted us with no problem what so ever). When we past through immigrations/customs I asked about this form but they said it was not necessary at all. Maybe this is because they are now eu?
But what are Guernsey/Jersey then?
Ps.
I know there are people who fly from the UK to EHMZ (Midden Zeeland) which is nothing more than a grass field. customs is available from Vlissingen (Flushing as it is know to the british). I have no idea if you have to prenotify them or if they just get a message based on your flightplan?
Things are possible with local connections. I was told personally by an Italian pilot (nobody on EuroGA) that he flies between the UK and a certain small Italian airport which has no customs. It’s near his home…
‘I know there are people who fly from the UK to EHMZ (Midden Zeeland) which is nothing more than a grass field’
I fly there from UK probably 3 times a year and have done so for years, and have never notified anybody, not even on the FP,
sometimes the customs turn up and check the passports but there has never been a problem, like Texel they are always
pleased to see visitors from the UK.
And actually its quite a decent ‘grass field’, they also have bikes for hire so you can explore Middleburg, and Veere .
Regarding EHMZ, the Dutch AIP is confused between “customs” and “immigration”, apparently:
( see http://www.ais-netherlands.nl/aim/2014-05-15-AIRAC/eAIP/html/index-en-GB.html )
However it does make clear that filing a flight plan is not sufficient:
I briefly checked the airfield’s own website but did not find anything relevant.
Things are possible with local connections. I was told personally by an Italian pilot (nobody on EuroGA) that he flies between the UK and a certain small Italian airport which has no customs. It’s near his home…
Has nothing to do with having connections. AIP GEN 1.2 refers.
Has nothing to do with having connections. AIP GEN 1.2 refers.
Detail?
