I would try to use one company to do both jobs - ppf and ceramic, to prevent them playing off each other.
You might be interested in the ceramic only quote I had from Azuri (I've since had a quote for £800 for XPEL ppf), the process they will undertake (inside and outside), timescales and the guarantee. Its far from the cheapest quote (not the most expensive either - Topaz is), but I'm convinced they're the best value I've found.
This thread put me onto them and there are other recommendations there.
Anyway, that quote:
Below is a quick overview of the process we will follow for detailing and ceramic protection:
The first thing we do is to carefully wash the vehicle, then carry out a multi-stage decontamination of paint and glass to remove any embedded iron and tar deposits that may have been picked up during the car's life so far during storage and transportation. This is an essential step to ensure the surface is safe for machine polishing. This consists of two chemical stages followed by a clay bar removal of any remaining contamination.
We would then carry out a two-stage machine polish process. The first stage is to gently compound the clear coat to remove any minor surface micro scratches, defects, etchings, sanding marks and swirls (typical on all new cars). This stage will ensure the paint (clear-coat) is completely free from any defects.
The second stage of machine polishing is carried out with finishing compounds to refine the clear coat to the highest possible gloss and sharpness of reflections. This is another essential step to ensure the paintwork is in the best possible order prior to the application of any protection and will really improve the paintwork against when it left the factory.
We then apply a professional grade, ceramic coating to the paintwork for protection.
We apply Gtechniq Crystal Serum Ultra ceramic coating, which is the very best coating available and one of only a handful available that offers true paint protection. It forms a chemical bond at a regulated temperature with the clear coat and is guaranteed for 9 years.
This is then topped with two coats of EXOv4, which is a super slippery top coat, designed to give excellent water repellence and help in making ongoing cleaning very easy. The EXO is good for a couple of years dependent on storage and use etc and can be topped up easily enough (happy to explain this in more detail if needed).
The wheels undergo the same decontamination process as the paint and glass (including chemical softening of tar spots then physical clay bar). We then liberally coat them with a high temperature tolerant protective ceramic barrier against brake dust, iron deposits and road tar for ongoing ease of cleaning/maintenance.
Interior leather is carefully cleaned to remove any unwanted oils / sheen and it is then protected with leather guard. This helps protect against dye transfer on light coloured leather and helps prevent leather sheen that can make an interior feel older than its years.
Glass receives three coats of Gtechniq G1 Smart Vision Glass, which beads water and is a semi-permanent coating designed to last up to 20k miles. We don’t recommend applying coatings to the windscreen.
Any interior fabrics, along with carpets and mats are protected with I1 Smart Fabric to protect against spills and scuffs. I remember on Steve’s job, we also treated the fabric within the extendable roof.
Rubbers, plastics and external trim / tyres are dressed for final presentation.
We charge £945 plus vat for this service and we would ask that we have your car for a minimum of three days to complete the work and allow coatings to harden.