Now, granted this is something you can’t really do yourself. But again, if you can teach yourself or have lessons and trust in your own ability; you could potentially do it. This is not fully recommended though as it needs to be done right, otherwise it could both look bad, and could not be completely waterproof.
This could mean damages with your house, and roofing is pretty expensive in England as it is. And the last thing you want to do is add more money because of something you did.
In our opinion leave it to the professionals, and this is who we recommended. They also provide any clothing items you may need. Right now they only cover Kent. Our you can contact them and see if they can sort a deal with you with their Facebook page here: