Maths degree entry requirements - Access to HE Diploma?

Basically what it says in the title.

I'm 33, have no official qualifications past GCSE, and am attempting to piece together information on how I could work towards a degree at this stage in my life. Due to general life things, studying locally in Middlesbrough is my only option.

I'd always dreamed of studying mathematics, and was happy to see Access to Higher Education Diploma listed as a potential entry method onto the Teesside maths degree. However, it states the following:

"Access to HE Diploma (with merit in at least 12 level 3 credits in mathematics)" - https://www.tees.ac.uk/undergraduate_courses/Mathematics/BSc_(Hons)_Mathematics.cfm

I've been informed by Middlesbrough College that there's no such thing as an access diploma with 12 level 3 credits in maths, and enquired at the given email address for Teesside Uni about what exactly this means but had no reply.

So basically, does anyone out there know if it's possible to study Maths at Teesside without A-levels and with an Access to Higher Education diploma instead? Or am I just out of luck?

Thanks.