What you will not find on the UKBA website very easily.

For English Language certification, it is much easier to just take any of the accredited English language exam listed by UKBA. My good lady went for Pearson Vue - PTE Academic which she sat for without review. The test took 3 hours and the result was emailed immediately within the same day it was taken.

The other route that you may consider is going for the English Language Assessment by UK NARIC. One of the requirements listed in their website is 'a photocopy or scanned version of a certified translation in English (if necessary)' - my loved one complied to this by submitting a description of all.

All the above takes time as per my loved one's experience. 1-2 weeks to obtain all documents from your university and 3-4 weeks sending/receiving docs from UK NARIC via email or post.
My loved one had her 2 degrees certified (De La Salle University) and found to be equal to UK degrees. You will receive a letter of comparability as proof of reference.

Check on the UK Naric link below for clarification.

http://ecctis.co.uk/naric/

Thanks for this Timmers, you just answered my question.

I was going to give it a go with my wifes degree certificate but realised it would be some job to meet their requirements. Plus, from talking to them it became obvious that it would end up as a refusal, owing to the nature of the degree and where she took it. The easiest option was just to do the language test.