I've not made any cheeses that have had fruit added, so I can't add anything on that. Boofer has ventured into this arena though with some blueberry cheeses. As I recall, it will be important to balance the acidity of the fruit with that of the cheese.
Anyway, I know some people say that you can eat Wensleydale around two months, and maybe even one month. I've not tried it that young, in part because I use caerphilly has my short aging cheese, and I tend to age mine out to 4 months or more. I've only made it a few times, though, but my 3rd one was a great result. I should make another some time soon.
If you want a decent, fairly fast aging cheddar, then I would recommend caerphilly or lancashire. There are a lot of people making caerphilly these days, so there's no shortage of experienced makers who can offer advice. Lancashire, which is ready in 2 months, was quite popular a year or two ago, and there are a number of threads on it to get ideas from. I've just got a small wedge of my last one left.
To improve, I really can't stress enough the importance of taking good notes. Even caerphilly will take 3 weeks before you should cut into it. You're not likely to remember if you went a bit over, or stirred a longer, or roughly, etc, 3 weeks later. Write it down as it happens, write down things you notice and/or do as it ages (i.e. flipped it and noticed it was wet, wiped off with paper towel, and re-salted - or "wiped it down with 4% brine again this morning", etc). These notes, and observations at the time, are a real help when you want to recreate a cheese later, or if you think you could improve something (i.e. too salty, not salty enough, too wet, too dried out, etc). I went over my make notes for my 9th caerphilly, which turned out dry and flavourless, modifed my make for my 10th caerphilly, and that one has turned out fantastic. Without details, I wouldn't be sure what it was that went wrong or what to do to fix it.