Okay first of all, ditch Reggie Yates as a style icon aha. Sorry, but every time I see him he's wearing a t-shirt longer than his blazer and his nipples are half out.
Secondly, what problems are you having with fit at the highstreet stores?
Thirdly, as for outfits, most of my looks follow the standard shirt, trousers/jeans, shoes and a blazer.
If you're trying to keep an urban feel to things, why not swap the shoes for some smart, white canvas trainers? There's a good article about them here on Fashionbeans if you can find it. Then a slim, minimalist pair of dark wash indigo jeans (don't listen to what everyone says, I buy mine from Topman and they're fine!). If you insist on wearing a tee instead of a shirt under your blazer, keep it simple. Minimalist stripes or just a plain white tee always works a treat.
If you're looking for a blazer, it depends on your price range. There's some Holland Esquire ones on TK Maxx at the moment and I've just bought one, although it hasn't arrived yet. If you're new to the whole thing, more important that you get into shops and work out your size. Tbf, Topman blazers have nice designs, even if the quality is a bit shoddy. Zara's a step in the right direction, but you might pay a bit more.