I also paid off my mortgage in full and have never regretted it.
However, some time after doing so, I strongly recommend that you pay £3 to download a copy of the title register from the Land Registry, just to check that the lender's charge on your property has actually been lifted.
A few months after I paid off my mortgage the Woolwich tried to repossess my house because I'd not been making monthly payments. (They'd lost my payment!). Then, when they found the payment, they tried to charge me over two hundred pounds for the interest that had built up between me handing them the money and them eventually crediting it to my account. Eventually (after my threat to involve the local media) they backed down on that and I thought that everything was settled. Then, over a decade later I tried to sell part of my garden to a neighbour, only to find that I couldn't because there was still a charge registered against my property, in favour of the ruddy Woolwich!