Oh goodness, OP. The things you could have done with a lump sum like that 
If I had that kind of money given to me, I could clear every penny of old student debt I have off, go on a nice holiday, save enough to cover all of my bills for the next year, learn to drive and take my my dd on some day trips with whatever was left.
I don't think any parent hands over an amount of money such as that, unless the family is a very wealthy one, without it being meant for something 'big' - paying off debt, buying a car, putting towards a house deposit or a wedding, etc. I haven't read the full thread but I have to ask - why have you spent £8000 so frivolously? Would it not have taken your mum a long time to have saved? Even if your mum has inherited the money somehow, surely it has taken somebody somewhere a long time to accumulate such a sum? I can't even afford to save £10 a month for my little girl right now, so I hate to think of the time and sacrifices it would take to save £8000 up for her.
I would personally be utterly ashamed of myself if faced with your reality - that will sound harsh, but I just mean that that's how I would feel, not how you should feel. But honestly, I would spend my time dreading my mother ever asking what my plans for the money were. I wouldn't know how to tell her and frankly, I'm not sure she'd want to hear the answer in your case...