Kidding, of course, but a rowboat would be low cost, but you’d have to
tow a second boat to haul your drinking water (or desalination device)
and food. Or catch fish, and have sushi for every meal.
There is no need to tow a second boat, one will be enough. But the trip will take at least a month in each direction, and the scenery will not be that exciting. https://en.wikipedia.org/wiki/Ocean_rowing#Atlantic_crossings A sail boat sounds easier though…
You can generally find flights within Europe pretty inexpensively.
Find which major hib is cheapest and easiest from your city london,
Amsterdam frankfurt paris etc..then see what a connection costs on a
budget carrier. Just leave time enough to deal with a late flight or
something. We have done this and saved hundreds on more expensive
The problem is that since Adria went bankrupt, connections to Slovenia has been limited. And there are not that many low cost airlines flying there either. But, it is a small country so the easiest is probably to find a flight to a nearby airport and make the last part of the journey on the ground. I'd suggest Zagreb, Venice or Vienna. Klagenfurt and Trieste are closer, but those airports are even smaller than Ljubljana.