I haven't with enable.uk.net, you need to make sure their awarding body is credited (can be used at Universities), sometimes you can call up a university to check the company is okay and accredited.
I used distancelearningcentre.com and they were fantastic. I little pricey compared to other sites but when spending over £400 anyway, you don't want it to be dodgy. They used Ascentis as their awarding body.