Advice on purchasing a first mens' suit?

Those of you who have been following my answers here and there will know that I’m transsexual, female-to-male, and pre-op.

Right now I’m planning to buy my first men’s suit. But understandably I have a body shape that’s not particularly average as far as mens clothes go. Now I can’t afford to shop in the kind of place where I’d get properly measured and fitted – my budget limits me to Asda or Primark (the UK equivalents of Walmart). So I need to do the measuring and fitting myself.

Vital statistics are as follows: Chest size a shade under 36”. Jacket length would be short as I’m only 5“6”.
Waist 32”, inside leg 30”. Pants are easy enough, I’m lucky to not have much around the hips and a 32” regular fits me well.

Fitting the jacket is the problem. A 36” looks right around the chest and shoulders, but too tight around the waist. A 34” is out of the question, I can’t even fasten one up. A 38” fits better around my middle but looks too big in the chest. So I’ve tried on all combinations and I can’t decide which is the best option.

There are “slim fit” jackets which are even worse but there doesn’t seem to be the opposite – a “comfort fit” for guys with a bigger waist in proportion to the chest (god knows why not, the beer-gut seems to be the standard male shape round here).

Now obviously I can’t afford a tailor-made bespoke suit so my question is, which would look the least ridiculous/most normal – to go with the smaller jacket that’s a little tight around the middle? Or to go with the bigger one that fits the waist but looks bigger up top?

Another question – which style would look the most flattering on my shape/height – two buttons and longer lapels, or three buttons with shorter, higher lapels?