My mother's favorite flower was the gardenia. I have found that gardenias are very particular in their growth requirements and I have always grown them in containers to provide them with the right soil and to be able to move them around in the garden in order to find just the right lighting conditions to induce flowering. The type of gardenia which you are interested in should be purchased only after you have a thorough knowledge of its growth needs for flowering success and that the place you have for it matches these conditions. Perhaps a plant less particular would do.

Gardenias are not really hardy in most of Britain. One hard winter and it would be gone.

Owdboggy's right, Gardenia is hard enough to keep going indoors in the UK, and certainly won't grow outdoors. There is a Gardenia called 'Kleims Hardy' that will grow outdoors here, but in my experience, its a poor grower and doesn't make much of a show, getting, if you're lucky, about a 9 inches tall and wide in 4 years, although it does a little better in acid soil. Lavender needs full sun and free draining, more neutral to alkaline light soil.

Hsve you asked your nan how she would like the front garden to look? How big is it in terms of length and width, and what's the aspect, and by that I mean does it face north or south or whatever? Does it get lots of shade or not much at all, and is the soil light and sandy or damp and heavy? Are you in a colder or warmer part of the UK?

These are the things you need to consider first before deciding which plants you're going to put in, because different plants need different growing conditions. If you want more advice about what will work and what won't, more information and preferably photos would be useful.

I was going to say that as well - do ask your nan what she would like. She may have favourite flowers or shrubs. Bear in mind that a small patch of grass will need cutting and edging regularly and this can be fiddly in a small area. The garden you have suggested sounds very attractive but is one that will need a lot of constant care to keep neat so you need to consider whether you can commit the time.In a small area less is often more and keeping simple can be more dramatic unless you are going to be giving it daily care.

If you have pebbles next to grass the grass will row sideways into them unless you are very careful. Do also check that your nan likes them -she may be a pebble hater like me, though they do have their place.

Lavender sounds a lovely idea. it prefers light sandy soil so check that this garden is not heavy clay before you buy any.
I can't think of any white flowers that will flower reliably a long time at the same time as the lavender but have you thought of using an evergreen with silvery leaves that would stay nice all winter? Have a look at Euonymus fortuii "Emerald Gaiety" (not "silver queen" which would get too big)

Do beware of choosing plants by just looking a pictures of the flowers on the internet as you need to know the size, hardiness, flowering season and ease of cultivation.
(Good think you checked about the gardenia...)Come back to us as often as you need to,and try to answer as many of Bamboo's questions as you can.

Good luck!

Just thought of a white flower to go near the lavender - Penstemon Wedding bells should flower at the same time.