Thanks for the second opinion Tim, much appreciated. I'm a lawyer myself, but this obviously isn't my area. Given that under mum's will I'd be a co-beneficiary and co-executor, it wouldn't be a DIY, let alone throwing in the complexity of a trust. Mum relies on me a lot, and also generally doesn't trust/want to pay exorbitant lawyer fees! I really just needed a starting point.
So, if your replies had came back as "no, can't be done" - that would have helped me in deciding on whether to spend time/money chasing that path.
Your reply along with Rob's ie. yes it can/might be able to do... get a solicitor...expect to pay a decent amount for it - are helpful too - it just means a different conversation with mum.
I can't believe mum doesn't have a will. She really doesn't appreciate the complications of dying intestate. After going through my grandfather's probate last year, as well as the increased possibilities of Covid-19 cutting short lives, especially in older generations, it's really put the importance of having a valid will in focus.
Thanks again