Remember you don't just need to use the plants I have suggested below.  In fact I actively encourage you to go to your local garden centre and have a wander around & see what is in stock that catches your eye. 

Remember certain types of plants are more easily available at certain times of year, so you may not always find what you are looking for.  Ask the team at the garden centre as they are often able to order plants in for you. 

I also recommend you look online.  Below are some links to recommended plant nurseries.