Personally I would say no, Shakespeare uses Lear's character to convey a political point which he supports as opposed to Lear being a portrayal of himself. When the play was writtern James I was king and it was he who believed in uniting Scotland, Ireland, Wales and England as one. Shakespeare believed strongly that splitting the country up would have terrible effect on the country and that this shouldn't happen. In this, he uses Lear's insanity, loss of all possessions and death by griefence to convey a very strong opinion on, in his mind, the catastrophic consequences that splitting the country in any way would have.
Hope this helps(it may not) x