Ideally you need to check with your bodyshop as to what and when you can apply any coatings or protection layers. They usually recommend a high grade Carnauba wax.
The OPT opti-coat is an amazing product. It is something that you can apply yourself although you do need to have the right conditions to apply it - i.e. it must be in a dust free environment and have a minimum temperature of 12°C for 24 hours while the application cures, however it will not fully cure for about 12 weeks. You need a clean surface free from contaminants to enable a good bond and flaw free finish. If the surface is dirty, or has imperfections, you will seal these in, so any which promise the earth without a little preparation first will not give you a flawless finish. You can pick up the Opti-Coat kits for around £40.