Thanks for your responses. The solicitor is sending me some information so I think I need to have a good read of this and make my decision, what keeps coming back to me is her saying 'you don't have to do this' as I think she understood that I am feeling pressurised to take control by my uncle. Thanks again.
You don't have to do it. Neither does your uncle. It's actually very sensible to have a good think at this stage, and to consider one's own circumstances and what taking on this extra responsibility would mean.
To put it simply, what's in front of you if you go for it is the following.
The deputyship application. Basically some forms that you fill out with factual information about your mum and her circumstances. Or you can give the information to a solicitor and pay (your mum's money!) them to fill out the paperwork.
Once you become a deputy you get a court order which details what you are allowed to do.
You show the order to anyone you have to deal with on your mum's behalf.
You pay an annual bond from your mum's assets.
You pay an annual supervision fee from your mum's assets.
The supervision level depends on your mum's assets and your ability to handle everything. If the assets are substantial or you (or they!) feel you need help there will be more contact. This can be phone calls, emails or visits from the Office of the Public Guardian.
Once a year you're asked to submit a report. You go over any decisions you may have made and reconcile income and outgoings (basic maths).
If your mum's assets and income are low there are exemptions as far as fees.
If you feel that this is not for you, and your uncle still feels the same, the court will appoint a panel deputy, quite often a solicitor. The up side is that if that happens the responsibility is no longer yours. The down side is that there will be a professional fee attached to everything the solicitor does for your mum and, ultimately, they get to decide what happens, not you.
Good luck with whatever you decide. Just to let you know, I'm a deputy for my mum and my husband's aunt, both have fairly complex finances, but I'm coping, and have been for several years. It gets easier. In the end you just get on with it!