I am lookin at the roof of this old hse I jus bought and was advised to get it fixed – coz the weaving seems ‘out’

I have a couple of choices
1) change the rooftiles completely – gonna cost a BOMB
2) treat the current rooftiles & rearrange them back
3) just rearrange them back

with that three options, I guess I should also install insulator and all. I heard of vry good comments of TSL.

Anyone can advise me on what I should do? and since im renovatin the whole house, I guess I should start with the roof 1st? A latest cost list would also be helpful. Thanks in advance.