RE: After prep what do I do?
After the de-tar and claying - you will need to give it a quick wash and dry. The paintwork is then ready for polishing. It sounds like you just want to give the car a bit of an enhancement, so even if you were to use a finishing polish on a finishing pad, it will make the paintwork pop. After machining the whole car, you will need to wash out the lubrication oils, of the polish, from the paintwork, so another fairy wash down. At this point the car is fully ready for whatever you decide in terms of protection.
If you are looking for durability, then you are looking at nano sealants; over a years durability, but the offset is that they are a little trickier to apply than traditional waxes and sealants, and if you get it wrong, you will have to machine polish the coating off. CarPro Cquartz UK Edition, is specifically designed to work in our (UK climate) so it cures better than their regular coating. For example most need to be applied in a fairly controlled environment, usually around room temp, without and massive fluctuations in humidity, which can be hard when leaving it set for 24hrs. The UK Edition can be applied once over 5 degrees Celsius and not as fussy when humidity changes. A nano coating will give a more glassy appearance than depth and shine, but you arent concerned about that, and also, its better suited to lighter colours.
The other option is a durable wax or sealant, that you might have to top up every 5-6 months.
RE: After prep what do I do?
What waxes or sealants would you recommend too? Once every six months seems perfectly grand to me :)
RE: After prep what do I do?
The Wolf's Chemicals waxes are very durable, but a bit of effort to apply and buff, but most will be if you want durability.
Chemical Guys JetSeal109 is a nice sealant.
Collinite 845 leaves a very nice finish but may not be quite as durable...4-5 months.
All will need two coats, and to be washed with pH neutral shampoo.