i have bought lantana plants from B&Q

They are tender perennials and usually treated as annuals as they dont winter well in temperate climates. You have the shorter one so it should flower for a while yet.

I'm afraid that they are a little on the tender side. They may survive a very mild winter in a sheltered spot.

You could try bringing it indoors or into a heated greenhouse or conservatory, if you have one. Or take cuttings to overwinter on a windowsill, like fuchsias.

They are root hardy down to about -4º C, but usually die out completely below that. If you have a sunney window indoors, you could try taking cuttings long enough to sit in a glass of water in fall--before frost, of course--and grow them indoors over the winter, to plant out next spring.

I had a Lantana that I bought in the UK, and managed to overwinter it last year and it grew new leaves in the spring, each stem is now about 15 inches long.

The way I did it was:

1) Kept the plant in a greenhouse.
2) Wrap bubble wrap around the pot.
3) Do not water, if watering use very little, scarcely.
4) Put a frost cover over the plant and leaves.

The plants leaves had fallen by springtime, and I pruned the plant stems down to about half of the size; and new leaves appeared as the weather improved and temperature increased.

At that point I watered it, and gave it some fertiliser.

It is still alive now and the main "trunk" has thickened.

I will be doing the same this Winter, and it will be in it's third year.