Tri X 400 is the classic reportage film — grainy in a way people actively want, and hugely forgiving of exposure errors. It's the safest first black and white roll.
Slower stocks like T Max 100 give much finer grain and smoother tones, which suits still life, architecture and anything you'll enlarge. Fast film like P3200 is for concerts, night streets and dim interiors where you'd otherwise miss the shot.
Black and white film has real exposure latitude. If you're unsure, err towards overexposing slightly — thin negatives lose shadow detail you can't get back.
Most black and white film needs traditional chemistry, rather than the C41 process used for colour (with exceptions like Ilford XP2). We can handle both in our Cardiff lab.