Pay off mortgage or invest?

Turkeyhill

Hi there,
I have been a long term user of the site ,but have now decided I could do with some advice. Quick bio ,same job 25 years recently paid off all debts loans etc ,only now have mortgage outstanding. I will soon be in a position to either pay off my mortgage of around £50000 with my retirement lump sum which is also around £50000. I intend to take a 2year holiday, renting out my house , My question is ,should I pay off my mortgage?thus getting all the rent money into my pocket or should I pay of half? leaving around £25000 to invest but using the rent to pay off the mortgage, or should I invest all £50000 , again using the rent money to pay the mortgage.I have spoken to a few friends and they all have different opinions ( all valid) just wondered what the good folk in MSE land thought. Just a foot note my bank will charge me .5% of the value of the mortgage every 6 months, as a charge for letting it out with their permission, (how kind of them!) Any advice is greatly appreciated ,