Shrub suggestions for tree line please

[Isthisreasonable]

Boundary between my house and next door has a line of mature trees on their side. A couple of conifers but some others as well (half a dozen in total). There's no fence but a few ancient concrete posts. The soil is heavy clay and it's south facing. On my side there is about 18 inches/half a metre deep border followed by the drive.

I would like to plant some shrubs to fill the border to make it more attractive. In an idea world something I could eventually keep 3 ft/1 m high and about the depth of the border so that it doesn't encroach on the drive. Not worried about colour.

I did think about pots but realistically I don't have time to be watering them during the summer months as it would take quite some time with the quantity required.

Any ideas? TIA.

Skimmia japonica rubella? It’s evergreen & has lovely little flowers the bees love. We give ours a light prune by running hedge trimmers over it once or twice a year. We have one that is massive, as the previous owners didn’t do anything with it so it’s really wide & tall, but we there is also one that is in a small border and it’s easy to contain so that’s why I’m suggesting it. We also have a thick clay soil.
www.rhs.org.uk/plants/94155/skimmia-japonica-rubella-(m)/details

You could look at Olearis haastii, evergreen, pretty flowers in summer, which bees love, which go to seed quite prettily too. Dead easy to look after.

Most of the viburnums would work although you'd need to keep them pruned. Some are winter flowering and some evergreen.

Philadelphus have some dwarf varieties, Choisya will grow in clay and has nice glossy leaves and white flowers in summer. There are minature hollies too.

If the planting area is heavily shaded by the existing trees during the summer months, then flowering shrubs might not do particularly well under there, so maybe go for something like euonymus as they are evergreen and come in different variegated varieties.

Dwarf Azaleas would work. Lovely colour in spring.

Thank you for all your suggestions- some great ideas. It's not heavily shaded as the neighbours have done a lot of pruning to reduce the height (down roughly to about 10 - 15 feet) and the overhang. Some of the trees have no branches for the first 4-5 feet.