Please DO NOT do the BSc at BCU in sonography. You need HCPC registration to practice and sonography itself is not a protected title. I do believe that BCU are scrapping it. This is why 95% of people do a BSc in radiography before going into another modality. Also, you need a PGDip for medical ultrasound to be qualified, not a masters. However, if you want a masters you can apply for that too.
I’m about to apply to do my BSc in radiography as a mature student but my partner is a sonographer and was a radiographer for over a decade. People are right on here that it’s very competitive to get on a training prep frame in ultrasound if you’re a newly qualified radiographer. My only advice would be to at least work as a full time radiographer for at least a year. If training posts still do not come up in your trust or you don’t land a place, look elsewhere. Hope this help.