Sorry that feels like teaching my grandmother to suck eggs,
No worry -all ideas and suggestions gratefully received! A few comments on them -Re Brú na Bóinne
Yes it would indeed be "doable" in a day!! You are quite the specialist in such trips - did you not do Parforce in a day from London?
As it happens we should (DV) be in Kazakhstan on the date you have identified but Dublin is a pretty easy place to get to on Ryanair from a multitude of airports and I am sure I could play tunes and find other "cheap flight" dates.
I think your budgeting is a bit "light" however - Mrs Meltwaterfalls needs to give you more training on that!
Petrol to and from NCL = £12, 1 day short stay Airport parking = £19 (unbelievable isn't it!!), 2 x flight = £64, 1 day car hire = £29 (With full CDW from a different agency - I am too risk averse to not have such cover. The £9 price doesn't cover the first 1500 euro which is too much for me and it goes up to £33 for "zero excess"!), 2 x entrances = £20, Petrol in Ireland (say) £6, Meals etc for 2 say £20. So c£170 for 2 pax = £85pp for a day return trip home to home. Almost as much per day as our holiday in S Korea which was £97!!!!
As I have already commented on this forum the "cost" of leaving UK is such that single day or even 2 day trips are relatively expensive and there is a lot more to see/revisit in Ireland so a 3 day/2 night trip (or even 1 further day) would probably be the most economic taking in all the Irish T List sites (and other things) and that is my "medium term plan" for Bru na Boinne. Re Corfu/Albania
In fact my "forward plan" for Albania is similar to yours, i.e via Corfu, but with a car rental from Saranda to pick up Butrint, Gjirokastra, Ohrid and Decani as well as Albania's T List sites (I last visited Albania in Enver Hoxha's time in 1975 so want to see all of the country when we are there). Car rental in Saranda is surprisingly cheap and allows (for a single payment of 35 Euro) the car to be taken into Greece, Montenegro and Macedonia (but not Kosovo which will need a taxi). A car rented in Greece for instance CANNOT be taken into Albania at all. So I could pick up Greece's northern nomination for 2020 of Zagorochoria.
Re car rental - As stated above, I prefer to have full CDW, but this can be a lot more expensive if bought at the rental desk. Some people take out an annual CDW Excess Waiver policy but I prefer to have as few different organisations involved in such matters as possible and have found the following rental car agency very good. All their rentals include full excess cover and usually an extra driver included. They are quite a small company operating out of Dereham Norfolk (of all places!). See https://www.zestcarrental.com/
. If you feed in for a 1 week small car rental from Saranda in May it will be from £102 with CDW and extra driver!! (plus the usual extra if you also want to cover keys, tyres etc)
I have had a good experience of their "responsiveness" too. Once we were on a ship scheduled to call in at Ashkelon from where I had booked a car with this company. Whilst on the voyage, the destination was changed to Haifa!! In 3 hours whilst in Rhodes (3 days before Haifa), I contacted this company by e-mail, cancelled the Ashkelon booking and changed it to Haifa without cost and fully confirmed!