Hi Louise DD!!!
Faro is right with the fees, I had to do one last year, used a firm called SG International Legal&Tax Services, they were slightly under, but add on the IVA and you are within that figure.
I signed over a Power of Attorney in the UK, so didn't even have to come to Spain, people thought I was mad, but everything went smoothly, as far as I know. Had no real problems with this firm, responded pretty quickly to my calls and e-mails. Once everything went through, it took a while to get all the paperwork back, but everything was OK in the end.
It is best to get a few quotes, fees can differ greatly. It is not a cheap process though once you pay the legal fees, Notary in the UK, Notary in Spain, inheritance tax, etc, the list goes on.
Good luck, it can be a daunting task, especially when you have just lost a loved one.
Best wishes,
Matt