Discussions of whether what someone says is true or false are unhelpful. I prefer to treat everything as true, because it might be, and if it is, the person needs help. If it's not, and Whirly is a gullible idiot, so what?
Phoenix, this is PPRuNe, and sometimes people lie, so don't get too upset. Some of your story does sound incredible. I happen to believe you, because I had some incredibly bad experiences early on in my training, and I've heard of even worse ones. Perhaps the thunderstorms weren't forecast. It happens. I remember several of us trying to get back to Welshpool ahead of a scary and unforecast thunderstorm.
On the radio nav issue...pre-JAR, which was only a few years ago, radio nav aids were not part of the PPL syllabus. We all did our QXC without using them. I still rarely use them, and I've flown all over the UK, done the Dawn to Dusk twice, flown to Ireland and in the US, practically always using basic visual navigation. I agree with WWW that you should be proficient in that, and shouldn't need more for your QXC.
I understand your trusting your instructors and not questioning their judgement. We all do that, and you have to. I think those who question that have forgotten what it's like to be a student. Knowing WHEN to fly is much harder than knowing HOW to fly - but we expect instructors to tell us. OTOH, weather can always change, and you should always be prepared to come back or divert if you don't like it. I'm not saying you did wrong, just emphasising how it should be done.
One other point, which I found out after getting my PPL(H); it's very hard to know what you don't know. If your training has been incomplete, you rarely know all that's been missed out, and it's often rather nebulous things like airmanship points. I rather agree with WWW - at some point, find an instructor you trust, tell him/her the whole story, and go over things and try to make sure there are no gaps in your knowledge. It'll be money well spent I assure you. Whether you do it now - probably best - or leave it till after you get your PPL is up to you...but I did something like that and I wish I'd done it earlier!