Most art/design degrees outside of Oxford/UCL will likely consider you as they'll put more emphasis on the portfolio (those two however are more academic and expect you to do a lot of writing, so expect a full complement of A-levels, particularly one or two essay based ones), but check with the individual institutions.
Some courses like Architecture, or specialised Engineering Design courses where a significant part of the course is a traditional engineering curriculum, will want standard A-levels to ensure you cope with the other non-design elements (in common with the above). For most courses like Fine Art, Graphic Design, Fashion and so on they'll primarily look at your portfolio though and usually don't have many formal requirements beyond token passes in 1-2 A-levels (or equivalent BTEC etc) plus foundation.
If you have only one A-level and no other equivalent qualifications (level 3) you may benefit from and want to consider taking an A-level in Art History if you can find a provider. But in the first instance, check with universities you're interested in and see what they think; many like the UAL will consider you (as they only require 1 A-level, 3 GCSEs and the foundation).