Last gen Fiesta, current Micra or Fabia are ideal.
Both are safe and cheap to insure on a 1l.
Most mass-market superminis start to wearout beyond about 60k miles. I'm thinking Fiesta, Corsa, C3, Punto, Clio etc. The VW-group cars (Polo,Ibiza,Fabia) seem to last better but are more expensive if they go wrong.
While you do need to consider your needs I'm afraid insurance will still dictate what you can have until your no-claims builds up a little. You may be old enough to get fast-tracked insurance so you gain 1yrs NCB after 10months rather than 12 to help you towards a better car later.
Don't worry too much about performance initially, go with what you can afford to learn to drive and repair. You'll learn plenty about driving quickly even in a 1l (conservation of momentum etc).
Happy hunting