What a great project, there's so much that you could do.
Aunt Sally beat me to the potager suggestion.
I'd be inclined to look towards 'pretty' varieties:
eg runner beans up the walls (flowers usually prettier than climbing French beans). Pick them form the bedroom window! (Not my idea - Joy Larcom's)
Leeks stay in the ground for a long time - maybe interplant blue and yellow varieties.
There are varieties of 'cascading' cherry toms that should look good in hanging baskets (again if you have a wall)
Throw bags of compost over a low boundary fence and plant things like strawbs in the 'saddlebags'
Have seen some purple-podded mangetout.
Rainbow chard looks great anywhere.
Rosemary as an edging plant. The flowers look great if not trimmed too frequently.
A single sweetcorn or three would give 'height'. I'd be inclined to grow some elsewhere too, then cut off the male bit when it's full of pollen and hand pollinate the female tassels on your specimens, then you might get a crop too even though they are not grown in a 'block'.
Oca has a lovely trefoil leaf which is edible and acts as a light excluding mulch for summer weeds.
Chinese greens/pak choi/mizuna/mibuna are very quick growing and picked as a cut and come again crop will fill space quickly if lettuce gets boring. At the right time of the year pak choi grows quickly and is more productive than cabbage.
The list is endless. I think that it will be great fun looking at the winter seed catalogues in a completely different way. I think that you'll end up planting a lot of different varieties, albeit in very small quantities, though so you might want to get involved in seed swaps, or choose seed that will last for a few years.
To keep it looking pretty for as long as possible I think that you'll have to raise things in modules and plant out at the appropriate time, so plan for a cold frame/holding area in the back garden.
Have fun,
Wish I had a front garden too,
Regards,
SS