emmscrow, Yes there have been lots of posts about Theodolite. But, never the less they are approved by EDI (who are approved by UKBA) and as you say close to you.
The cost is the same as anyone else. Why not give them a call. They can advise you which test to take. It's very basic. Cost should be within the range I said.
I don't know if British Council are close to you?
The objective for you is to get that all important piece of paper that will be accepted by UKBA
