Oh that sounds very nice. We have a Victorian terraced cottage... so we're probably going for a similar look.
I would avoid poisionous plants (foxgloves, delphiniums etc) unless they are right at the back of the border. You don't want small people eating them.
I planted some lovely bits last year... but had a baby this spring and it all went a bit to pot. That said it does mean that I know what will grow well by itself with the minimum of looking after(!)
Definitely our best buy was a mallow plant (Lavatera). Lovely pink flowers all over the bush and grows like mad without you having to do anything.
Rosemary goes well with lavender. But also needs to be in the sun or goes brown.
Crocus will tell you when to plant stuff.
For a cottage garden I am currently craving... Phlox, penstemon, verbena, alliums, agapanthus, roses, astrantia, salvias, veronicas, sweet rocket, hollyhocks and lots of herbs.
Pots with cut and come again salad are good too. Looks pretty and saves you a fortune. Grow from seed any time from spring right through. Some of our lettuce survived the snow in january and my neglect