Trains in Europe (again)--recommendation

I have to be in London at the beginning of April.

I have to be in a tiny village in Navarre 20 April.

I have to be near Sibiu, Romania early June (but need at least a day in
Bucharest first).

In between, I'd like to take trains from London to Pamplona, with a few
one- or two-day stops along the way. But not too many, because I want
to bicycle from Pamplona to Zamora before I report to Villamayor de
MonjardÃ*n on the 20th.

From Villamayor, bus to ?? and then train to Bucharest around the
beginning of June, Again, a few one- or two-day stops along the way
would be nice but not to delay my arrival in Bucharest/Sibiu very much.

Earlier, someone suggested night trains, to save lodging costs AND keep
the day free for wandering. Sounds good.

Low cost would be nice, too. Maybe a pass would be worthwhile. While
working in Villamayor, I pass my 62nd birthday, if that affects prices.

Recommendations?

--
Wes Groleau