How about popping into your local garden centre to see what they have in stock this weekend? Coolings, in Rushmore Hill, Pratts Bottom, have a fine selection of plants at reasonable prices - and some special offers.
Today I purchased a pretty dwarf rhododendron in a ceramic blue pot (pictured) for, what I consider good value, at £29.99, plus 4 for £18 trailing fuschias of various shades of red and purple.