Examcentrelondon

I’m looking to do iGCSEs next year as a private candidate for Edexcel English Language, Mathematics, Further Pure Mathematics and Physics before moving on to do A-Levels to go to university. I found examcentrelondon that does all the examinations I want to do but I can’t find many reviews on them and that leaves me a little worried about whether or not they are/might be a scam. Has anyone used examcentrelondon before?
Also does anyone know any good private exam centres in the Lambeth Borough area that allows private candidates especially if they are cheaper as I currently am on benefits so money is a bit tight. Thanks in advance for any advice and help