Well you can offer �7.50 an hour to the lady in question and see what she says - you could always leave it open to negotiation - not necessarily salary, but increased days off, flexible hours etc. to make it more attractive.
If she wasn't interested you could try the school / college leaver route. Minimum wage is �3.40 for school leavers under 18, �4.60 for 18-21, and �5.52 for 22+
So you could say, �5.50 an hour to rise to �6.50 an hour after 6 months (as you would have to train someone with no experience). That would be a nice rate for someone still living with their parents, no real 'bills' and saving up for house deposit / car / other stuff etc.
Obviously it would be preferable to hire someone with experience, preferably through word of mouth. But there are some gems out there who just need a bit of training and you have yourself a great addition to your workforce.