sindri59 san,
With pleasure
When you have questions, feel free to ask me.
MMM san,
Thank you for adding useful expression
I totally forgot "行きたかったら", though I frequently use it.
sunflower san,
as MMM san said, it is hard to recognize the difference between "行きたかったら" and "行きたければ".
To me, the former is just a little bit casual; the latter is slightly formal.
I don't think "行きたかったら" has "when" connotation -- no offense, MMM san!
Well, honestly, Japanese language has a lot of expression to indicate just one meaning.
行きたいのでしたら
行きたいのであれば
行きたい（の）なら（ば）
行きたければ
行きたかったら
These lines mean "if you would like to go"; the first is polite and soft; the second is very formal; as for the rest of three -- it's hard to explain... Still, they indicate "if you want to go"
