Two minute whiteboard video plus v/o

Need a corporate explainer whiteboard video created for me,1-2 mins long, possibly first of a series. Sparkol is fine, and I will supply graphics and script needed. I need the script delivered by a professional-sounding Uk accent voice, preferably female, and I would prefer to be able to approve sample/portfolio of artist before commencing. I am a stickler for grammar, spelling and pronunciation- but very open to artistic guidance and ideas on best way to deliver the message. I would prefer someone who took a little longer to do a quality job, than rushed to deadline...