Gardening at the roadside

I have been thinking about ways to make my (hopeful) future space as productive as possible. While I like ornamentals, I am most motivated by growing things I can eat (with attracting pollinators and growing green compost also important). So, until I have more space for fruit and veg than I can handle, I want to pack as much as I can into every available bit of garden. 

I am going to have a reasonable size south facing back garden (hard to be sure on Google maps, but I think around 112 square metres, or 1200 square feet for the old'uns), though some if that will end up being paths, shed, pond, compost bins etc. However, there's also a smaller north facing front garden. The top bit will be very shaded by the house for most of the day, but the bottom two thirds look like they may get a bit of sun as there isn't really shade from the east or west. In an ideal world, I'd like to get some fruit and veg growing there as well, but I would want to grow things that will be okay next to a main road. I'm thinking leafy things and herbs will be difficult to wash, but perhaps there are other options that would work well? 

Until I live there, I'm not going to know for sure how busy the road is, but I don't think it is going to be too bad. Although it's a main road, it's on a spoke that just leads up to the top of the (populous) village (where there are a couple of schools and a GP surgery) then out into countryside. I don't think there will be heavy traffic. So, hopefully it will be okay to grow some food there? 

I'm looking for ideas of things that will be easy to wash, won't look a mess growing in the front garden, can cope on a slope, and don't need too much full sun. What do you think?

Fruit trees like apples and pears. Dwarf ones but you won't be picking fruit from them for a year or two.
Herbs like rosemary, bay and thyme aren't difficult to wash - the fluffy leaved herbs like sage may be.

I am very wary of growing fruit near a road, but as a precaution I would grow a hedge to act as a filter, an evergreen like privit or yew, which though slow growing means less work required and possibly a more dense shield

I think I would have to steer clear of fruit trees as they would be within 5m of the house and that could cause problems when it comes to selling on. I'm hoping to get a couple of dwarf fruit trees (maybe an apple and a plum?) in the back garden, but the front garden is a bit short for that. One day I hope to manage a garden big enough to squeeze a mini orchard in, but not yet!

I was thinking maybe slower-growing root vegetables like parsnips and onions. Perhaps rhubarb. They may not look very pretty for the front garden though. Maybe interspersed with some flowers to try and make it less allotment-like?

Privet isn't slow growing (maybe in the far north?).

We have a holly hedge at the front that only need a cut yearly, is dense and stands up to the muck and grime off the road, mainly from farm tractors haring by. It cn be kept are any hight needed. A lot of books suggest morello cherry against a North facing wall if you have one.

You can plant anything you want on your land within reason. In my first house, I dug up the front lawn and planted potatoes. Next doors were horrified but the lawn was a mess and needed sorting. The potatoes were a one year catch crop. Root veg would need washing wherever grown but need light to do well. Goosberries and black currants would be OK and are easy to wash. Red currants are more delicate. I've seen leeks and onions growing in a front garden among the roses.

If you think the back garden is about 112 sq m, that's about the size of a half plot on an allotment. Perhaps concentrate on getting that productive and, once you have, then think about the front - by which time you'll have a better idea about the environment.

Mark I was referring to the yew being slow growing, though I think cotoneaster is one recommended against pollution, with Holly a good one for sound

My question is - what is planted there now? If it ain't broke, don't fix it until there's time and need to change things.

It's mostly lawn currently.