Hi there - I have been in a similar boat and have been conditionally accepted onto the Science & Engineering Foundation year at Loughborough to start in 2012 at the ripe age of 24, with a view to progressing to the Chemistry degree thereafter.
The entry requirements are quite flexible for mature students. One accepted route is 60 credits with the Open University, of which at least 30 must be in maths/science. Mine were all at level 1 and it didn't cause any issue. I believe that the OU charges have changed recently, but it may be more time effective than A-levels. The OU course costs would be around £2,500 for 60 credits. Student loans are now available to cover that, but this may impact on eligibility for student finance on the final degree, but SLC should be able to assist in that regard.
The only other minimum requirement for Loughborough foundation year is a C grade for GCSE Maths and English. Your post is not clear as to whether or not you have those...
Hope that helps, best of luck.