I'm a woman, but these are my cycletouring clothes:

Cycling-specific:
Cycling shorts
Leg warmers
Plain short-sleeved jersey
Helmet
Gloves
Cycling shoes
Cycling vest
Cycling jacket

Not Cycling-Specific:
Plain wicking T-shirt
Plain long-sleeved merino wool top
Black fleece jacket
Convertable pants
Baseball shorts

I especially like the plain wicking T-shirts because I can wear them while cycling and still hop onto a train or go into a cafe and look relatively normal.

When I know my day is going to be a mix of activities, rather than cycling all day, I like to wear the convertable pants or basketball shorts over my cycling shorts, so again, I look relatively normal.

I get these things from places like:

Anaconda
Decathlon
MEC
Sierra Trading Post

You should have a Decathlon somewhere close to your area. It's French, but I know there are some in the UK too.