Wimbledon is 4 months away baby. Venus is generally very busy with business engagements etc. So I doubt she will stay there mowing the lawns and eating strawberry & cream for 4 months until the tournament.
I honestly wouldn't even be shocked if she came back to the states before heading back over there.
At the moment we are all in the dark regarding her comeback unfortunately so it's hard for us to give advice. If it were me I would buy the tickets, and then you can re-sell them yourself if she doesn't show? At this point I think you should just make a decision either way and then see, because it seems to be quite stressful for you my dear. We hope she shows up!
'All roads lead to Wimbledon' is something she has said before tbf (even in a YT video from years ago), I think she's just hinting that she's planning to play that tournament. Which is great for all of us!
I think it's highly likely she will play a warm up as well (probably Brum since she's played it before), but that's just my guess
Hopefully she's not entering her Serena teasing/catfishing/hinting era though.