Amateur alert....

I'm hoping for some general advice about where/how to plant new stock.
I moved into a new flat last year, with a garden that is shared with
the flat upstairs. I live in the South of England. I'm a bit of an
enthusiastic haphazardist when it comes to the garden!

My garden is SoutWest facing, fenced all round, not very large (15M
long?) and a bit damp (the lawn is all moss, and, I think, none the
worse for that!). Mine is the bed on the left, which spends much of
the day in the shadow of the fence, which is 4 or 5 feet high. The bed
on the right is not mine, which is galling because it is truly
sun-drenched! My bed does get sun, (as evidenced by the ENORMOUS
Rosemary bush there) but not a vast amount. There is also a bed at the
(South Western) foot of the garden, which is against a 5 foot tall
wall, (no early morning or late afternoon sun.)

Now, I went absolutely mad at a garden centre last week, and am now in
possession of: a Ceanothus, a Lilac, two small Delphiniums, a small
white Peony plant, a three foot tall Wisteria, fragrant Jasmine, an
Iceberg rose, three Margaritas, two large (1'6" diameter) pots, a
small Broom shrub, and a number of small plants I couldn't even
identify but which are very, very pretty... ahem... Where should I put
them all! (There's really not much space!)

The bed on the left, as well as the Rosemary mentioned, already has a
honeysuckle, a bed of gladioli, two rose bushes and a baby apple tree!
The bed at the foot of the garden has herbs and bulbs...

My thoughts at the moment:

In the back bed (by the wall) the lilac in the left corner, (for shape
and form I think that's best, and it'll get loads of sun when it
reaches 5 feet!) and the ceanothus in the middle, trained against the
wall. In the left bed, in the lea of the fence, from left (closest to
the house) to right, the jasmine (to climb up the fence and up the
house) and the Iceberg rose, sort of next to each other. Then comes
the honeysuckle, which forms a neat 'pillow' level with the top of the
fence. I plan to plant some of the weird little plants here! Then,
between the honeysuckle and the Rosemary (about six feet) there is a
patch of Gladioli and a small rose shrub and an embryonic Phlox
(sp?)... I was thinking of putting the Delphiniums here. After the
Rosemary bush, then, and just before the apple tree, I thought perhaps
the Peony.

The margaritas in one of the pots. I have NO idea where to put the
Wisteria!

To those that have made it down to here, I'm grateful and impressed!
Any advice for me?