That is a very interesting question. There are shedloads of good-role-model celebs who speak with what linguists call received pronunciation (RP), also known as the Queen's English.
I speak with a northern-cum-midlands accent, a result of my peripatetic childhood. I don't think it would sound authentic or right if I learned RP. It would sound as if I had gone all posh. Indeed in engineering, RP is a positive handicap: it would be considered snobby.
Trouble is, there are very few celebrity role models with lots of footage on YouTube you can play again and again to learn to copy with a regional accent like mine. The nearest I found was Carol Vorderman, who coincidentally is an engineer by training. I greatly admire the way she manages to convey the I-have-a-working-brain message while being really quite boldly feminine.
Her voice is a bit too high for me to copy – she is quite soprano – but I can have a great time trying to learn her voice and other mannerisms.