As above-these quote apply to ANY INTernational TGV/hispeed train to/fro FRance, also for inland TGV, but then you get lower surcharges of 10/20€ for IN/beyond quota.
You are most likely aware this is 2nd Easter day, last day of for many a long 4-day weekend off and hence a major busy travelday, so I do not give you much chance on earlier/later trains too.
In general it simply is a pain to use those hi-speed trains with a pass, even more so in ESpana then FRance/TGV-the pass should be used for slow regional travel to enjoy the sights, experience a lot of local/regional trains and local sights/cuisine etc. Not really for just skipping off a few major cities on anybodies 1st time todo list!
ALT should be obvious: flexible, or use plane or bus-a normal busticket (today its mostly flix or blabla) is often cheaper as the surcharge for €* itself. (30€ usually). If really lucky the bus (coach for british) might even go by train across the tunnel! The ALT of the pedestrian ferry via the classic Dover-Calais route is however fraught with difficulties. See seat61.com for finer detials. If this ALT is no option for you-as it seems to apply for many here- then others will know possible ways around.
Note that if you decide to fly then-the pass is also valid for trip OUT of UK valid to any airport and on same day also for further travel from destination-if there are trains there.