I used Reep they have depots across the UK. They installed Llumar PPF but another popular one is Xpel.
I do nothing different when washing the car because of the PPF, the only thing i don;t use on the PPF is tar and glue remover or any other harsh chemicals.
We have a Up Gti on order and have had a quote to PPF that but costs are making it a hard decision. Maybe just a good paint correction and ceramic coating instead, it wont help with stone chips but will keep the paint looking good.