@Travelcrazy @heldinadream I would advise against buying anything from Gardening Express. A quick search on old threads will be revelatory.
Also, Phoenix palms are not reliably hardy in much of the U.K. I have one and I love it, it is huge and spectacular, but my garden is very sheltered and a sun trap and tbh I’ve just been lucky that it’s survived. If you want palms, look for trachycarpus fortunei or chamaerops humilis, both of which are much hardier than Phoenix and better suited to containers.
As @Yamadori suggested, other hardy evergreen plants that could give you this Mediterranean garden feeling would be sempervivums (houseleeks), which are very robust succulents and come in lots of shapes and colours. I also agree that it looks like a banana at the back. I have dozens of them, they are very easy to grow but they need full sun and they look awful in winter.
For container planting I would also recommend soleirolia soleilrolii (aka mind your own business ☺️), it’s a moss-like plant, very invasive if planted in the ground but looks stunning in pots. Also evergreen. https://www.rhs.org.uk/plants/17471/soleirolia-soleirolii/details
Another evergreen is Daphne, smells divine too but very slow growing so you will need to be patient and buy the biggest you can afford.
I would also recommend ferns, many look good throughout the winter and are nearly evergreen - you just need to cut the old fronds in spring and the new fronds unfurl immediately. Hart’s tongue fern in particular might look similar to some of these tubs.
You could also try aspidistra, it’s sold as a houseplant but is quite hardy.