The difference is so small so I’d guess that there is no immediate need. When starting out with quads I had a 25m line set and a 15m line set. Had a couple (~5-10?) sessions on the 25m, before going on two week vacation to a place (in Devon btw) where the beach only permitted the 15m lines. I also point to my previous answer to the beginner line length question ( viewtopic.php?f=7&t=13837#p138526 ). That being said, on a longer timescale you should get both longer and shorter lines (~3.5m – 40m) to be an as complete quad line pilot as possible and get a possibility to learn from a slightly different feedback. If pursuing with quads you should get various vented quads, possibly an indoor one, vary the LE stiffness by different spars, try non Rev-like (Hadzick-wings) quads…

A cheap way to progress and open up to frequent practising close to home (dependant on your area of course) is to make a short line set like 10m or so to make use of small fields/empty parkings. Extra cheap if you have an old broken dual line set around somewhere. OK during the phase when the unplanned landings are frequent you might want to stay on the 65ft lines, but on the other hand the walk of contemplation gets shorter with shorter lines. You can quickly launch again with short lines. While at it, my advice is not to wait very long going short lines just because it feels comfortable with longer lines. In general being comfortable with and learning something new is not the same thing. Polishing and building a firm base is something different but not any lesser. Go short line when (or just before) ready for it and kite “everywhere” and don’t care what any neighbours would think! My short line and my no wind kiting development got delayed by such considerations.

But currently, during your first sessions there is so much new to learn, so first get acquainted with the procedure and equipment. To increase the number of available sessions get a vented quad (apart from “For Sale & Wanted” in Fractured Axel you could try the “Börse” of Drachenforum). No more frequent crashes?– get short lines also.