First thing: it isn't soft/med/strong tension, it's the weight of the string. There may be a slight difference in tension when in tune, but that is most certainly not your current problem.
Beware of things "they" say. If the strings are brand-new, they will sound metallic until broken in - as a beginner, probably 3 weeks of practising time.
A Gear4music cello is, pardon my French, a piece of shit. You can't get a playable instrument for less than a couple thousand $US. But you've got it, so just plan on trading up in a year or so (I like the Eastman Chinese series, but there are other good student models as well). If money is difficult, look into a rental from some music shop. That may work out better.
In any case, with a low-end cello like your Gear4Music, you might find some strings that are a bit less screechy, but it's really not worth it since you're a beginner. I would expect that your teacher will concentrate on fingering positions, bow hold, bow stroke, etc., and worry about tone quality rather later on.
PS - general note to all beginners: the most common cause of a busted string is tuning very sharp. Always tune from "below" to avoid overtensioning. (My personal shame is busting a C-string that I misidentified and tried to mount as a G-string. SNAP)